Any PS3 can get the YLOD if subjected to too much heat.
I understand you being nervous about it (I was when I bought mine (even though it was a refurb unit)).
If it YLOD's due to heat, you should be able to fix it at home with a few tools and a little bit of "tender loving care".
Just run the hell out of it for a few days and see what happens.
I don't know where you are located but if you have Craigslist available (and don't want to (or are not able to) mess with it), you can find someone pretty reasonable in price that will fix it for you.
I got my 360 free (then added in $75 for a charger, power cord, a couple controllers and batteries that he had no real use for) because it had the RROD. Fixed it good enough to last about a year (I beat the hell out of my systems due to traveling in an rv 7 or 8 months out of the year). It RROD'd again and I didn't have time to dig out all the tools, go get more stuff and fix it myself. Was leaving the next day on another road trip. Brought up Craigslist, picked through a few adds until I found the one I liked. Talked to the guy on the phone for a while then took it over to him to fix it for me.
The entire repair (because he had everything sitting in front of him) took about 30 minutes and cost me 35 bucks.
It has worked flawlessly for almost 2 years now.
Personally, I wouldn't worry about (and I don't) the YLOD until the day it happens.
That is the best answer I can give you on it.
As for the PSN account.........
I know it's possible but somebody else will have to "pony up" the answer for how to do it.
I don't do PSN so I would be of no help with it.
Seriously, you might try a google on "how to transfer PSN account to new PS3".
I'm sure that might give some info.
Good luck and will check back in the a.m.
I would much rather go to my grave not needing my gun, than go there wishing I had it.