Should cargo ships be military or civilian? If they have to be civilian, can you still boss them around if you make them or is that in the hands of the computer citizenry?
Always make everything you can civilian. The savings on maintenance costs and no maintenance failures (which means no overhauls either) is super helpful.
Question: Is it worth loading a ship with a veritable shitton of low-accuracy high firepower 10cm gauss turrets? Because I figure a quad gauss turret with 5sec ROF and 32 shots per volley, even with 17% accuracy, could be mighty lethal. 10 of those turrets (armored) would only require 2,300 tons, and would put out 320 1-dmg shots every five seconds. At 17% accuracy, that is an average of 54.4 hits every five seconds, which equates to 54.4 dmg (on average) per combat turn. If I did my maths right, that would mean 3840 shots and 652.8 dmg per minute, 230,400 shots and 39,168 dmg per hour. Is this actually worthwhile?
Gauss can be quite lethal if you can actually get within range of the target, and the first few smaller sizes are good - but I wouldnt go with too small. Without taking into account other things (crew grade, etc) 10 size 0.6 guns at 10 accuracy each means on average you'll hit 1 volley every time they fire, but one size 6 gun at 100 accuracy means you hit one every time they fire. All shrinking it did was make the gun less reliable, because sometimes you won't hit at all and sometimes you'll hit more than once.
I often go to the 5 size for 85% accuracy or the 4 size for 67% accuracy, since crew grade can make up for most if not all of that at point blank and 15% accuracy for a 16.67% size decrease is worth it by itself for the size 5, but none of the smaller ones are worth it imo. You also have other things that affect the accuracy - the fire control range rating is 50% accuracy at that range, point blank is 100%. And like I mentioned crew grade gives an accuracy boost too, sometimes a substantial one considering how good your crew is. The 34% bonus crew aboard one ship I have made firing a weapon at the 75% accuracy range an accuracy of 109%, which made actual accuracy with the 85% turrets 92.65%. At point blank they were getting 146%, which would mean a 97.82% hit rate even with the size 4 gauss weapons.
As far as your sandbox game, starting with all techs is just going to slaughter everything and get boring. Will take you longer to find something to kill than go in and kill it, even invaders
Seeing as I only use 2 twin-turrets of ultraviolet 15cm lasers, I think that's a bit much. But what do I know? Barely anything.
Anyway, what's a good % of oxygen to pump into Mars? Around 20%, as that's what Earth has?
0.1 is all you actually need, so I'd go with 0.1. The thing is you can't have oxygen at 30% or more of the total atmosphere, so with 0.2 you need more other gases to make up for it. With .1 you can get away with half the other gases and have it terraformed sooner. You can always go in later and add more gas if you just want to make it like Earth, but it isn't necessary.