You can use PSN SEN Enabler Disabler or if you Rebug CFWs, you can use Rebug Toolbox and switch the mode from NORMAL to REBUG.
About what you need to download to not get banned, well... OFW 4.31, play original games on a homebrew-free PS3 and not use cheats, I never heard of anyone doing that and getting banned, so I guess It works.
There is StealthMan, PSNinja and maybe some other apps, I feel like they hide homebrew only while Sony can detect If you're on CFW or OFW so they don't help much (I could be wrong). Sadly, there is no way to guarantee you won't get banned. I've been getting on PSN since the first release of FckPSN and somehow managed to survive all the ban waves, everytime I play online I use games with BD and not backups, but I really doubt thats really a way to avoid bans, I think I was just lucky.