About the terraformers, I tried a small one and a very very very big one.
The design is minimalist, just enough engines to have a slow speed of 400km/s (they are supposed to pass most of the time around a planet, not moving), and nothing else.
The small design have only one module, and it came at a cost of 686 BP.
Then the huge design, the Atlas, have 100 modules! And it came at a cost of 58930 BP. 85% only of the cost of 100 small terraformers. So for me the big design is better. But it need a titan shipyard, not a problem for me since I needed to make several Atlas to terraform Venus (I actually have 5 Atlas, removing a total of 3atm per year! In less than 30 years Venus will be colonisable!), and also wanted to make a giant asteroid miner.
Here are my designs:
Atlas class Terraformer 2 638 400 tons 23075 Crew 58930.4 BP TCS 52768 TH 21875 EM 0
414 km/s Armour 1-1700 Shields 0-0 Sensors 1/1/0/0 Damage Control Rating 1 PPV 0
Maint Capacity 14 MSP Max Repair 500 MSP
Terraformer: 100 module(s) producing 0.4 atm per annum
C- ICF Drive E0.225 (100) Power 218.75 Fuel Use 2.25% Signature 218.75 Armour 0 Exp 1%
Fuel Capacity 1 500 000 Litres Range 45.4 billion km (1269 days at full power)
This design is classed as a Commercial Vessel for maintenance purposes
Earth Cracker R1 class Asteroid Miner 2 546 050 tons 44155 Crew 59980.8 BP TCS 50921 TH 21875 EM 0
429 km/s Armour 1-1660 Shields 0-0 Sensors 1/1/0/0 Damage Control Rating 1 PPV 0
Maint Capacity 15 MSP Max Repair 120 MSP
Cargo 400000 Cargo Handling Multiplier 200
Asteroid Miner: 400 module(s) producing 14400 tons per mineral per annum
C- ICF Drive E0.225 (100) Power 218.75 Fuel Use 2.25% Signature 218.75 Armour 0 Exp 1%
Fuel Capacity 4 000 000 Litres Range 125.5 billion km (3386 days at full power)
This design is classed as a Commercial Vessel for maintenance purposes