No need to for a lower version as it plays less games as newer games need high FW PS3's. Upgrade to 3.55 original firmware then go to 3.55 custom firmware. If you ar eon a 2.XX FW there is no jailbreak as the lowest one there is for that is 3.15 and that is for otherOS support. Staying on 2.XX would just be dumb as you lose features and can play even less games. 3.55 users have a 100% compatibility right now thanks to managers using usb mount.
There is no such thing as going on PSN "SAFE" with a CFW, while you can go on no problems there is no safe way. Never has been never will be you are gambling with your deck going online but as you will learn even a banned deck can go online right now, just not sure how long it will last.
PS3 CECH-2501A [CFW] & CECH-3001 [OFW]/ PS2 SCPH-3901 & SCPH-7501/ PS1 SCPH-5501
Mod Cobra 4.46 v7.00 w/ E3 Flasher [CFW] & Cobra ODE 4.50 [OFW]/ Mod HDD-OSD [Phat] & Modbo 4.0 [Slim]/ Mod MM3
HDD 1tb [CFW] & 640gb [OFW]/ HDD 640gb & OPL v0.92 w/ 1.5tb SMB