Questions About New JB Methods, Firmware Versions, Bootroms, Etc

I'm on a launch-day 3GS, firmware 3.0, Jailbroken with Purplera1n RC2. I do NOT have my files backed up in Cydia). I use a PC for all of my JBing/iPhone stuff, I don't have access to a Mac, and I'm not sure which iTunes I have. I was meaning to upgrade and re-JB to 3.1.2 but by the time I went to do it 3.1.3 was out so I couldn't get 3.1.2 signed. I want to preserve my ability to unlock in the future (for resell value, I'm on AT&T) and it's my understanding that I can't do that with the current JB method for 3.1.3 on a 3GS. I haven't been to the forums in a few weeks so I'm not really current so I have a few questions:

1 - Has anything changed in terms of upgrading to 3.1.3 and JBing while still preserving ability to unlock in the futre, or is that still a no go?

2 - What is this new "spirit" JB? Would that allow an updrade to 3.1.3 and a JB that preserves my Baseband/bootroom (whichever one deals with unlock ability, I get mixed up)?

3 - My friend has a refurbed 3GS running 3.1 and he wants to JB. He had an original iPhone the he jailbroke so he knows the terminology and such but isn't sure about all the hardware/process differences on the 3GSs so I told him I'd find out for him. Instead of starting another thread I'll just ask here. I don't think he cares about preserving unlocking ability so A), Can someone provide steps for JBing 3.1, and B), Could someone do the same for upgrading to 3.1.3 and JBing (with a PC by the way)?

Thanks in advance fir any help, and sorry for the long post