2. No. Wouldn't make sense to me, lore wise. Check the references regarding Isengard on the Nan Curunír page.
3. Could make sense.
4. Won't support this. Geography is similar to the Enedwaith.
5. See 4.
6. No point in this point as it concerns a suggestion on the LOD.
8. Here's the code that makes Ring of Isengard the generate in the Nan Curunír biome. I'm sure if you would have useful suggestions or even ready to use code to add more elements of Isengard and/or details to the wall, Mevans would appreciate if you'd share it.
9. Isengard already has a decent amount of units ... idk if this would be useful with respect to gameplay balance. Any supporting arguments?
11. Nah ... I'd prefer an Isengard structure representing the industrial nature of the pursuits of Curunír when he ruled the place: quarries/mines with large furnaces fed with the log they plundered from the Rohan Uruk Highlands.