Hey, Pacsonic. Much of the text in SoR2 is ASCII and can be found via a search in the rom. The titles in the credits appear to be compressed images. I haven't really tried to locate them, but running tracelogs and looking for LEA functions might get you there.
The names in the player select screens are sprite tiles, four per letter. Modifying the bytes in a few offsets will help revise these.
For sounds, try downloading gsaurus' MDV utility. It's part of his Pancakes of Rage suite. There's a guide in it that has all the banks and offsets for voice clips.
If you're looking at SoR1, not sure I can be of help there. Never played it.