Thanks for playing and taking the time to write all this feedback!
1) Pacing: We're working on a sandbox mode that'll have more customizable pacing. Also wanna add more difficulty/accessibility options in the future.
2) Meat shields: Yeah, that's just a bug/unfinished.
3) More complex/meaningful economy: That's our goal too! We're still experimenting with some ideas how to get there though.
4) Soldiers on walls: Ideally we wanna add stuff that'll enable you to keep the soldiers relevant in the late-game.