but you must remember in the first one qui-gon said i am only a protector i can't fight a war for you! but in the second there were seperatist formed and a army comisioned the fact that there were two hundread on geonosis was because it was pre-emptive before a main strike on the robot armys so in this case they needed the jedi!
no, they are keepers of the peace. but i think that all the jedi knew that the shit was gonna hit the fan. after all, padme would have been captured eventually. she was not there to sight see. remember when she said "i will suffer the same fate as my own people."? if the jedi had a reason to believe that a large scale battle was gonna take place, and that a sith lord might have been involved, then i think that more jedi should have been sent. by the way, jedi x. theres no need for sarcasm here.