Okay, problem #1 solved...
First, verify rpm2tar (or rpm2targz) is installed
# emerge -va rpm2tar
Once installed, convert it
# rpm2tar stuff.src.rpm
Then untar it
# tar -xvf stuff.src.tar
Now I have the following files:
Not sure what to do to move forward. There are no makefiles or anything to help me make an ebuildfile or tbz2file. The README.TXT only gives instructions on building an RPM, which I don't need.