Oh I see. Yeah texture export from RC is something that has been requested for a couple of years apparently but hasn’t been implemented yet. I hope it does get implemented because that would be really useful to me and I’m sure, many others.
In terms of quads: Yeah RC is a triangle system and I don’t think it can use or display quads so the method you’re using is probably the best for now.
I do something similar whenever my Z-Brush texture (diffuse) isn’t up to par. I bring the ZB model back into RC and generate textures. Then export the model from RC (which exports a mtl and texture map) and then I go into the folder and delete the obj and mtl, just keeping the texture for use on my retopologized ZB models (as the diffuse, in place of the diffuse rendered from ZB).