Mines can be upgraded. To restore arsenal you need bring miner to sietch cave. Look like visible infantry with big black bag. If the enemy kill thief before you bring him to sietch you will not get the spice. I think that thief should have every house.
Thief look like invisible infantry without rifle.
Fremen stealth trike - Invisible trike. Fremen Worm rider - Can capture the worm for these you should attach thumper and wait until the worm come and eat the thumper you should come to the worm and capture it. Than you can bring other units to the worm it can ride 5 units 1 worm rider and 4 any other units. When the worm is under your command you can view its health and the worm come to the sands surface. Worm have huge health can eat mechanic units, squish infantry and wery hard to kill but if all fremen on the worm are killed you will lost control ower the worm.