Personally I'd start with something a bit smaller.
I've recently starts making 'Asian' maps for CM:SF2, so I had to figure out my mapping techniques afresh.....I started with a couple of 640m x 640m maps to develop techniques, then did a 1.2km x 1.2km map using some alternative techniques, to widen my 'Asian' repertoire.
I'm currently struggling with a 2.4km x 2km 'Master Map' incorporating almost all of the techniques I've developed.....It's taking months to do.
As for swapping maps back & forth between games, allegedly it can be done (with many caveats), see this thread:
Sadly I couldn't get it work.
But I did download a lot of converted maps from those who could and who were kind enough to make them available.....Most of them worked just fine.