David

Hit the tilde key ( ` ) to open the console and enter the following.
setstage MQ202 160Esbern should open the door, and hopefully all will be well. If he refuses to talk after the above, however, enter the following...
setstage MQ202 170That forces Esbern's dialogue.
 
If all else fails, the following console command will complete the quest - A Cornered Rat.
CompleteQuest MQ202

When you do not feed as a vampire, your disease slowly progresses through 4 stages of severity. In your case, since you haven't fed in a long time, you're a stage 4 vampire (the final stage). Being in the final stage makes you a seriously vampy vampire; the majority of NPCs will attack you on sight until you feed again.
 
For more information on the stages and the easiest ways to feed, check out the vampirism guide I wrote ages ago.

This has happened to me too. Try the following.
Load an older save that doesn't crash when saving. Create a new save file (a new save through the start-menu; not a save over current file). Open the console and enter "player.kill" without quotations. Load your original save (the one that was crashing). Type in player.kill Test saving to make sure it worked!

This one?

Here are the containers that use the above design.
0004C6C6 : Aringoth’s Safe (TG02AringothSafe) 000D7770 : Niranye’s Safe (TGTQ04NiranyesSafe) 00102EB8 : Red Wave Safe (TGTQ02RedWaveSafe) 0010ACB6 : Safe (RiftenPawnedPrawnSafe) 000800E0 : Safe (SafewithLock) <-- Perhaps the only one with a lock like above? Forgot to check. 00103397 : Safe (TGREndSafe) You'll probably want to use one of the last three so it's just called "Safe" in-game. The last two spawn with pretty good loot already inside.

There's a similar bug in the wiki.
 
 360   PC   During a wedding with Brelyna, she may disappear.Solution: Sleeping and returning to the Temple of Mara may cause her to reappear, walking around the chapel's altar. The marriage ensues normally if dialogue is initiated with her. If she didn't even show up, all you can really do is go and sleep/wait in her home (The Hall of Attainment) and hope she shows up again. Your back-up plan is reloading a previous save.
 
If you play on the PC, you have additional options with console commands.

Under Settings there should be an "Invert Y" option at the top.
 
See if you can find this menu, and then toggle "Invert Y".
 

Unfortunately that speech glitch was fixed in Skyrim's 1.9 patch.

Use the following console command.
SexChangeIf you're not targeting an NPC / mannequin when you enter it it will change the sex of your character.

Try fast traveling to a city that doesn't have a wall and see if he spawns with you.
 
If you're on the PC, you can just type this into the console to teleport to him.
Player.MoveTo 97E1F

You can't directly command your housecarl to kill your wife. However, as Buttons stated, he will likely join in should you attack her.
 
Just be aware that if you kill your wife you will not be able to remarry.

Sonir?
 

 
Unfortunately you're not able to change bards in the Hearthfire houses; a specific bard is assigned to each property.  You should be able to dismiss her, though. I say "should" because there's a known bug that causes her to stay even after dismissal (but there are workarounds if it comes to that).

I have houses on each plot, but my favorite is Falkreath Hold. Putting a deck all the way around really lets you take in all of the scenery.
 

 
It's also the most temperate environment. No harsh winters or dangerous swamps.

Have you finished both Blood's Honor and Purity? You have to complete both to be able to remove them. However, if after having completed these quests you drop the heads and then pick them up again... They'll be stuck in your inventory.
 
Here are some notes for those who have not yet completed both witch head quests.
 

At or above level 20, the quest can be initiated by speaking to Silus Vesuius in Dawnstar.

When completing the subquest to gain Shadowmere, having a purchased horse with you can cause Shadowmere not to appear.
Shadowmere can be debugged after this happens by fast traveling to the stable of origin of the last owned horse. Shadowmere will appear here for a second and then vanish, and reappears permanently when you fast-travel back to the Dark Brotherhood Sanctuary. If you completed Stabilized in favor of Shadr, Shadowmere will first appear at the Riften stables.
If you have the horse Frost from the quest Promises to Keep, Shadowmere may not appear and fast traveling back to Black-Briar Lodge stables or Riften stables has no effect. Shadowmere will respawn by the sanctuary pool on your return from Solitude at the end of To Kill an Empire.
 Open the console, type prid 0009ccd8 and then moveto player to bring Shadowmere to your location. If this doesn't work, use player.placeatme 0009ccd7 to create a new Shadowmere at your location.

Unfortunately this likely isn't something we can help you with since it's dependent on what you've done with the armor. Check your usual storage places. Also, be aware that not all chests and storage places are safe to store items for long periods of time -- most of them actually reset after awhile and delete any stored contents!

There are three conditions that must be met to trigger the quest.
A counter starts at the beginning of the game which will increase each time you visit the city of Windhelm or the immediate surrounding area. When it reaches four, the Blood on the Ice quest will be available. The player has to enter Windhelm, either through the main gate, the docks gate, or by fast-traveling, between 7pm and 7am. The graveyard scene should then be triggered and the quest ready to go. Tova Shatter-Shield and Arivanya need to be alive. Since it appears you have met the first two conditions, I'd check to make sure Tova and Arivanya are still alive. 

Are you on the PC? If so, hit the tilde (`) key to open up the console, type the following command, and hit enter.
setstage MQ105Ustengrav 60That will instantly complete the quest.

This question is has been marked as a duplicate. For discussion and the potential solutions, please visit this thread.

Apparently I missed this when it was originally posted. I apologize. 
 
Hopefully you've found a solution by now, but since it may help someone else in the future I'll post my solution. You're fortunate because you're using the PC -- that makes bug fixing much easier!
Hit the tilde ( ` ) key (next to the 1) to open up the console. Type tcl into the console and hit enter. Clip through the door. Reopen the console and type tcl again.

I think this is one of those bugs that requires a reload from a previous save, unfortunately. Assuming you have the proper perk requirements and levels, of course.

Fan site / forum for the elder scrolls series.

Recommended
Windows 7/Vista/XP PC (32 or 64 bit) Quad-core Intel or AMD CPU processor 4GB System RAM 6GB free HDD (Hard disk drive) space DirectX 9.0c compatible NVIDIA or AMD ATI video card with 1GB of RAM: Nvidia GeForce GTX 260 or higher; ATI Radeon HD 4890 or higher DirectX compatible sound card Internet access for Steam activation Minimum System Requirements
Windows 7/Vista/XP PC (32 or 64 bit) Processor: Intel Dual Core 2.0GHz or equivalent processor (AMD Sempron @ 2.4 GHz) 2GB System RAM 6GB free HDD space Direct X 9.0c compliant video card with 512 MB of RAM DirectX compatible sound card Internet access for Steam activation More information, including specific hardware - http://www.uesp.net/wiki/Skyrim:System_Requirements

Sounds like a randomly generated event. Probably don't have to worry about it, it's just something that'll pop up occasionally like the usual road-thieves and what-not.