This is a quick and ugly depiction of the rules. Useful criticism regarding rules, gameplay, or things I ought to add or should change is requested. This is a complete and playable game at this point--if a rough one.
Judging the success of your rules may require one additional piece of information.
What fictional space combat are you most closely trying to approximate? From the nomenclature and general descriptions I would guess Mass Effect, Babylon 5, or Battlestar Galactica (in that order)
If you're not really trying to evoke an existing feel, then could you describe in maybe a paragraph or two what you'd like battles to feel like under this system?
For instance, I might suggest adding some kind of heat build-up mechanic; one of the uniquely scary things about fighting in space (if it could happen at all) is that you stand easily as good a chance of cooking yourself alive as you do of putting holes in your enemy. If you're not interested in that kind of brutal realism, though, that's obviously going to be inappropriate.
As to tone, it's meant to be a generic system to represent any kind of soft SF that makes some cursory effort to do damage control on the abuses of physics, so yeah, Mass Effect, Babylon 5 and BSG are all candidates (incidentally in that order), as are generic settings similar to them. Heat is something I'd like to add in theory, but in practice keeping track of the heat of 4-12 units in addition to their horizontal and vertical speeds and (possibly) available reaction masses is likely to be a nightmare. I'd assume that most people wouldn't be burning stupidly large amounts of fuel or overworking their radiators or heat sinks in a battle: the common sense of your imaginary officers is the justification for glossing over some of that.
I've used the word 'magnitude' too many times, I'll go back through at some point and separate some of the terms. The general idea of the above is to simulate escort squadrons as being dangerous but very fragile collections of smaller ships in between ponderous and incredibly well armoured capital ships. Whenever squadrons suffer damage, they suffer it right there, right then as ships explode and people die. Capital ships die a slower death, though enormous battleship grade super heavy murder death kill manly power cannons will probably wipe smaller capital ships out in one or two hits.
[Edit] I'll probably add in a bit about facing specific damage thresholds, so that ships can have really heavily armoured prows and weaker engine compartments. It would mean tallying damage up on a facing chart, but that isn't a problem.
I suspect that actually building ships or designing encounters under your rules may to be an issue--once different units are stronger or weaker than others, you probably have to figure out point values to determine what people can use. Also, I'm not a fan of dices that aren't d6s unless there is annother reasonable way--it complicates the game. Also, if you're rolling a d10, 2d6 may be preferable (more stable results, easy to find d6s). On yet a third note, once facing becomes an issue, you're going to have to work to explain why this is happening in 22 dimensions (why not fly up and target a ship's squishy bits from your new vantage point?)
On another, note, I think I'll steal your way of phrasing maximum speed: it's a whole lot clearer than mine.
The basics of building ships will be tricky at first, till I work out how much of an impact each statistic makes. As for 2d, its just a heck of alot easier than 3d, not even going to try and come up with fluff for it. If I want to play 3d space combat I'll play Saganami Island. I chose 1d10 as I planned to make the numbers quite large, 1d6 wouldn't have had the same impact and I'm tired of witing up d6 systems
It looks like you're developing a different system than me: it's probably in both our interests to split this into two threads and crosslink them: easier to get specific feedback on each one and less to keep track of.
Pretty much, though I'm just playing round with this as if it was a hobby horse, not something I'm truly devoted to seeing through. If I decide to update it, I'll send it to you or post it in spoilers again, but I shan't be posting a running commentary of my work so there isn't really a need to make a new thread.