1. To create INJ/REM files I use svdl'e "SpawnCharacterP6 update", or "Pozers Little Helper" (PLH).

SpawnCharacterP6 is good when you already have the morphs loaded a the character. PLH is good for making INJ/REM files directly from obj files, and is particularly useful when you need to make morphs from a morphed full body obj. Both the above are free. I think D3D's Poser file Editor, and PhilC's pz3 editor can also produce INJ/REM files, but these are not free, and I don't have any details on how they work.

2. The easiest way to apply textures and other material settings is as an mc6 or MAT pose file. mc6 files can be saved from the Poser Material Room, and can be converted via a simple text edit to MAT Pose if desired. As I understand it, DAZ Studio does not support the mc6 format, and for this reason many prefer distributing MAT poses. The choice between mc6 and MAT pose is controversial, and you will find many pro and con arguments in the forums.

3. UV regions will be stretched or compressed by the application of morphs, but I have never heard of anyone distributing new UV templates with their characters.