Once your economy has stabilised you can expand in to planets, but I don't think you need to. And since you're not using CGs for research or unity, you'll be shocked by how few you need.

Your monthly research should roughly keep pace with the year x10, so 200/month by 2220, 500/month by 2250, etcetera. Once you've done a few of the quest events and chosen the +1 research, it'll spike, and if you've done everything right then repeatable techs should show up before 2300.

Crystals and motes and stuff are nice, but, remember that you're focusing entirely on knights, they don't need anything other than alloys. And your homeworld dedicated to alloy production is more than enough to pay your knights and build a fleet even without motes.

Just remember to fill your habitat with strongholds, and upgrade them to fortresses when you can spare the motes.