I feel like I'm done waiting for NRT to become useable with JGR's Patch Pack, and want to attempt to draw and code a simple roadset and bridges for it witha GPL v2 license. Can I do that in NML, or will I have to code it in NFO?
AFAIK, if you're looking for sprite replacements, like TTRS, UKRS or ARRS, NML can replace base sprites, yes. You only will have to redraw them. There are pages on the tt-wiki about baseset sprite replacement with NML.
All my sprites (in CC or 2CC) are available here