It is not.
You instead have various ship modules available that automate most of what needs to be done on the ship so you can focus on just flying.

It probably wouldn't be worth doing. There's currently a solo loadout, which gives you AI turrets and a really lazy AI mechanic. If you play with more than one character in the lobby those AIs are going to draw far too much power, for balance reasons. So, while it would actually be somewhat helpful to have one character stay permanently seated in the pilot's seat while another runs around sorting loot, going on EVAs, etc. it's just not worth the extra power cost.

Edit: and trying to do this multiboxing instead of using the AIs would just be cranking the difficulty up to insane levels.

Multiboxing works in your typical MMORPG because you can see everything that is happening from one perspective. You be on your tank and just look around to see how your healer and your caster is doing. In VC, each role has a completely different perspective on the game. You can't see what the engineer needs to do without actually looking at their screen if you're the pilot. As a gunner in a fight, you're 100% zoned out of everything else going around you. You rely on the other players do perform these non-dakka tasks as you get those shots in. The engineer is basically completely clueless as to what is happening unless the other players talk about it. I know understand why Scotty calls up to the bridge three times per episodes to figure out what is going on.

You also don't have resources to spend like mana where it doesn't matter when you sit on it for a while. Actions aren't timed (like casting bars) and the moment you stop doing something with one character, that character is idle and useless. In target based RPGs, you still get their auto attacks. Here, you get nothing.

Yes, it is possible. But it is not easy.

Steam will need to have multiple instances running in their own virtual environments. You will need to buy the game for each Steam account.

Better just to have two different machines.