Might you have a screenshot?
It flees as normal, not reproducible.
It does look a bit choppy.. Not sure if something can be done about this easily or why it is caused..
Confirmed on 1.4.2
I followed your steps exactly, and the potion wore off exactly after the 0:00 mark, as expected.
It sounds like your server isn't updated to 1.4.2
It's very clear this is something specific to your hardware. If your 5 year old computer can't support some of Minecraft's parts, you shouldn't run Minecraft on it.
This sounds like lag.
From MinecraftWiki: Villagers will remove offers if the offer has been used some number of times and it is not the villager's only offer. http://www.minecraftwiki.net/wiki/Trading
Is that what's going on here? Do you think that's what's happening but the GUI is indeed failing to update?
That has nothing to do with the login server, it means the server you're trying to connect to isn't being run properly, whether that means there's currently an issue and it's not accepting new connections, or it's not forwarded correctly, or even your internet is having some kind of issue connecting.
Not really a bug, and like Talven said I'm rather fond of this specific "bug".
This issue is not reproducible, and seems to be specific to your hardware.
Closing because this isn't a bug.
Confirmed on 1.4.2. However, it seems that if you are in creative mode and you fly up past the block, you will pick the arrow up, and same in survival mode if you build up, but only once your feet are at the same level as the arrow. Not sure if this is intentional, but it doesn't seem like the right behaviour.
It is not possible to have the pig swim into water while riding it.
Confirmed on 1.4.2
The intent of the dropper is to drop items and nothing more. Period. Just because you want it to perform a certain way does not mean special functionality should be added to it diverting from its purpose, because other people probably don't want that. If you wanted to request that DISPENSERS spawn minecarts onto rails, that might be acceptable, but this won't happen as it goes against the whole purpose of the dropper.