1) You have no penalties to attack roll with a bow or crossbow while wearing a buckler. Even if it´s a normal buckler.
2) Being basically an "use activated" item, you gain the benefits of the buckler´s enchant... sorry, magic, whenever you use it. That is, I think you don´t keep the Haste effect, since you lose the AC bonus given by the buckler when you fire a bow; from the FAQ:
<<The Player´s Handbook says you can use a buckler and
fire a bow or crossbow without penalty. Does this mean you
get the armor bonus from the buckler while firing the bow
or crossbow?
No. You can´t use the buckler´s armor bonus during any
round when you fire the bow or crossbow. Once you fire, you lose the buckler´s armor bonus until your next turn.>>