I'm new to the whole PSP CFW thing and I've been searching and I need help on deciding which CFW to use.

I have a PSP 3001 that has 4g module, currently it has 6.20 OFW. Should I update the OFW to 6.39 or stay at 6.20? Also can I log on the PSN with CFW?

Also, in order for 6.20 or 6.39 to be permanent I have to run a certain file? In other words I will always revert back to OFW when I turn my PSP off, correct?