1 - I've already adjusted that in v0.92 so that PD Ships have at least one offensive weapon.
2 - Resupply Depots are available at odd tech levels of the Resupply Tech Area (ie 1, 3, 5, 7, etc)
3 - Remote miners are available at level 3+ in each resource extraction tech area
4 - It might have something to do with the changes I made with the AI and their anger level... I'll look into that...
Also there is a tech chart available for the Balance Mod:
http://www.captainkwok.net/balancemod.php