There is endless info and tools, on creating your own firmware, ask in the help and support if you need help, as it would be unfair to thread wreck this thread. if you need a starting place tho, find and download PS3MFWBuilder Portable and ps3mfw 02 both of them, sorry I don't have the links anymore.
I also found to get the best results creating your own firmware was using a clean install of winxp, none updated, with the minimal drivers installed and no .NET, anti virus or firewall installed.
No after you downgrade you lose the ability the play BluRay.
Sorry I can't upload my firmware, due to not wishing to break any laws, nor do I wish to work for facebook, sorry I hope you understand. lol