Different Tech Levels

[Elf Monkey]

Good afternoon everyone. First post with a desperate question.

I've recently written a campaign module (low-medium fantasy, low magic) but want to flesh out a few details. I'm having trouble with a specific area which is different tech levels. The campaign generally is TL3, there are some barbaric and nomadic peoples at TL2 but there is also a capital of an advanced but guarded TL4. They have developed gun powder use and such and have been affected by the fashions of being further advanced than the other local areas. I just wanted to ask all of you:

How do you think this will affect their ideologies and ethics, local area, economy, fashion, warfare, morale of the citizens, relationships with other communities... etc?

I'd really appreciate as much detail as you feel you can divulge as I'm really stuck on this. Especially economy as I'm very weak in this area.

Thanks in advance for any help.

Edit: I should also add that I have access to the Low-Tech book