new with a few questions?

[joesiphone]

Hi All,just a few questions,(Quick back ground, model#MB496CZ Using it in Czech Republic 3G service)I have a 3G that is factory unlocked,I was not that smart,installed the newest software from i-tunes which did the 02.30.30 modem when I first got the phone and did the activation,Then I found out about what is possible with the i-phone,performed the jailbreak with Quickpwn 2.2.5,it works very good and did not lose any data,I have loaded a lot of apps from Cydia,and everything appears to be working good,Also have tried other phone carrier from same country and it works, now what is.....
1) what is Yellowsn0w for, to lock it so you can use other phone carries?
2)what problems will with come from my 02.30.30 modem update when I'm in the USA,(My service in US is t-mobile)will I be locked in the carrier of that country cause of the update?
3)will I be fine and not need to worry about it cause I can still use any phone company now cause it's factory unlocked with jailbreak?

[alek]

If u r factory unlocked then no worries.

Yellowsnow snow is if you buy a 'locked' iphone and want to 'kinda' unlock it.

The Modem update will do nothing if u r facyory unlocked, u can still use any carrier

[JStraitiff]

a factory unlock has to do with the hardware you can do it yourself but its risky

but if it is hardware unlocked then it will never be locked again no matter what u do with software