yes but you have to know a few things:

1) not all apps can move to SD especially widgets should not be moved and custom keyboards such as swype
2) not the full app goes to SD but most of it does, some parts still remain in internal memory.
3) during your phone's first startup you cant run those apps that are in sd until they are loaded, it may take a while depending on the app size & how many apps in sd.

depends on how large these apps are gonna be, i would say yeah it should be sufficient if you're talking about 30 apps roughly but again, that depends on the size. 320mb is approximately about the same amount (or slightly more) than what i have on my nexus one, i need more than that but that's because i have lots of stuff on my phone. if you want a lot more then i would recommend getting galaxy S II instead or galaxy W (although the W and other samsung phones has its own share of limitations and 3 different storage types causing some other different headaches entirely)...