Not sure if #4 is only when walking or not, I'll have to see if it still shows the bonus in space.
-edit- Yea I just tested, its only when walking. Not getting the bonus when flying in space or skimming on the surface. Oh well, still a handy +1 MV when walking.
My other char kept freezing up when loading the save for some reason, so I made a new one. My very first mission gave me the option of joining the Silver Knights, and my joining bonus was a Mighty Firestarter Ice Wind with a bunch of crazy weapons. It had 4 incendiary missiles and 3 volcano rifles with -2,-3 for the stats. I modified it a bit and got the stats to -1,-2 and even managed to add an extra set of swarm missiles that I had looted from the mission target onto it. I'm not sure how it'll play yet, but I imagine it will be pretty lethal when I unload all those missiles.
Total weight is 47t, 29.5 body and 17.5 carried (absolute max on both counts without getting more negatives). It wouldn't have been possible without some of the items being reduced weight. One of the volcano rifles is 1t lighter and its ammo is 0.5 lighter, so thats 1.5t of carried free. Then the torso seems to be 0.5 lighter than the standard (compared to my other char's ice wind, anyway). One leg and one arm are also 0.5 lighter. So all total it has 3t less weight than normal. Without those it would weigh 50t and be over weight on both counts and it would be at -3,-4
In any case this is the first time I've even seen volcano rifles, so hopefully they work well. I've never used BLAST 2 BURN BRUTAL weapons before, but I have a feeling they're going to strip armor off stuff really fast.