Reviving a dead thread. Rise rise rise I give you life Frankenstein!!!
I had seen the text table/font when I was recently doing some rom hacking in a SNES game. It used 2bpp and when it was a sprite graphic or background it was 4bpp. I've used tile molester and tile layer pro they were both very similar. Most of the locations of the rom/ram were already known so I could look up the location online then plug those values in the software and go from there. It might be easy for an emulator/debugger. Just open the rom in hex and since most of the time you will see ascii text blocks just type that value in as a breakpoint and you might be able to find the location of the text table (if you can't find the RAM Map).
The palette is also stored in the rom at some location, again a ram map would make this much easier. Usually when editing a rom through tile editing software it won't change the default colors used in the game, although it certainly makes editing easier, and helps to know you're at the right location.
Finally, like others mentioned many times graphics and stuff are compressed. You will really have to know the location then! otherwise, you will see a bunch of scrambled graphics that won't help very much. For these locations you need to uncompress them, edit them, and then recompress them back into the rom.