So far as I know, only temporary root is available with z4root.
Where to get: [Q] Root for LG APEX - xda-developers
How to: Z4Root Is One Click Root App For Samsung Galaxy S / Android Phones
Without recovery, you can't do a full nandroid - the analog to your BB desktop backup.
However - with root, you can install and use Titanium Backup - my experience on my phone is that I manage to backup nearly everything, including my desktop layout. Don't know if that will apply to your phone or not.
One thing I never learned how to backup are my SMS's - but you'll find many capable, free apps for that in the Market.
I'm sorry - I have no info regarding custom roms for your phone, perhaps a check around this thread and chatting with others will yield more info - that's honestly the best I can suggest at present.