So I have a PSP 1001 running 5.00mm-3 and I've been wanting to upgrade my CFW to access PSN. I've been looking around some threads and have a general idea of what needs to be done but I still have a few more questions

What is the latest cfw that I should update to that runs isos?
Is a Pandora battery needed for any upgrades?
Will most homebrew that run on my current firmware still work? (AnyLanguageStudy, NZ:P)

Thanks in advance for any help