Aarimuff

Can confirm.
Happened to me in a Snapshot and saw not aanything bout it being fixed.

Can´t confirm for 1.8
Maybe try again in a creative test-world

Downgrading (from 1.8 to 1.7.9 Optifine) is not supported.
See https://twitter.com/jeb_/status/507198150474727424

And the "block lagging" is may caused by to high render distance or other settings.
Or does the first problem ónly appears on a server?
If fo the server might be lagging.

Can confirm for 1.8
However only on worlds opened to LAN

Edit:
For me the game only freezes (not responding) and I have to kill Minecraft via Task-Manager

Can confirm for 1.8.
But only if you use the "esc" key to get out of the broadcast menu.

Confirmed 1.8pre1

Can confirm now!
Blaze shot a Pigmen and all of them got agressive to me.
Relogged and Pigmen were friendly again.
Previous:
I think you meant "if hit by another Mob" right?
Cannot reproduce.
I think your pigmen were aggresive before a e.g. Skelton hit them.
Then they got aggresive to the Skelton and didn´t hunt you anymore.
If you kill the Skelton they will become aggresive to the players again.
(i´m not sure but thats the only thing I can think of and reproduce)

Cannot reproduce.
Could you record a short video to let us see that it isn´t working for you?

Replaces every block when placed on a Ladder (see gifs)

Confirmed for 1.8-pre1
Skulls and Heads however are dropped when redstone is placed underneath!

Confirmed on 14w24c!
On 14w34b this isn´t an issue for me.