1) Pretty much instant. Since the graphics are simple there's not too much to process -- it just changes. The only delay is if you have some macros to run -- a 0.3 second delay is always added between commands.

2) I assume you're talking about the 1x1 buttons? Frankly, I wouldn't trust them to anyone not experienced with remote controls. I myself can use them, but anyone with a careless finger is likely to miss. Good for obscure functions.

3) So far I haven't experienced ANY unusual behavior -- crashes, graphics glitches, etc. And I'm using very old video drivers.