Re: Commerce
I'm with the others that suggest that Commerce, in and of itself, doesn't provide enough of a benefit to be intra-competitive with the other industries. Making it a structure, on the other hand, would make it an "always." Personally, I like the ability to sell to my own colonies and have a one-stop-shop for things. I don't want to lose that. On the other hand, I see the dilemma.
Suggestion:
A basic open market opens with the initial space port. It's extremely stripped down: basic fuel, supplies, and the odd low-tier, common weapons. You can sell to it with normal tariff markup. It is an independent market and nothing you sell to it will impact the colony itself.
"Commerce" (the industry) replaces the old basic market and has some positive market multiplier (TBD), adds the buying/selling of ship hulls, increases the availability/quality of weapons, and reduces tariffs from 30% down to 25%. In essence, it creates a slightly player-friendly market that is consistently better than standard markets but no so much that you wouldn't go out of your way to exploit supply overages/shortages. Selling on this market will impact local supply/demand. However, commerce doesn't generate any kind of production in and of itself so it only really benefits that colony and nothing else. The trade-off, I suppose, is quality of life (for the player) versus overall empire health. I can't think of many scenarios where I'd want Commerce ASAP but with a mature colony, it might be a boon.
If Commerce remains an Industry (and I think it should), it just needs to be competitive, though in its own way.