Starting a RL1, Region Locked, All Bosses, No Killing Friendly NPCs, Only Weapons from Region. Need help with a few questions

I have a few questions since I'm new to the RL1 playstyle and haven't done too much outside a single RL1 base game playthrough. I have a few questions for this run.

1. Firstly, I thought of the idea of using only weapons found in the specific region I'm in, I havent checked if this is feasible and was wondering if this is a popular run type or even if this is a possible run? By that I mean, does every region have at least 1 weapon you can get before killing a boss?
2. Also, what counts as a region? Is it based on maps, or is Lake of Rot part of Ainsel River
3. Finally, what order would I complete the regions in? So far, I've completed Limgrave and am in Liurnia, but would Caelid include South-West Calid + Dragonborrow, or would I go to South-West Caelid, kill Radahn, then move onto Altus?

Any and all help is appreciated I really wanna make this run work but im struggling finding all the logistics