Returning player here. I recall how biochem and other skills used to provide items only available to players with the skill - is this still the case?
Girlfriend is playing a tank guardian and I'm playing a healer sage. We're picking up synthweaving and biochem, so it'd be great to have her critting better on the gear crafts, but I'm guessing reusable stim crafts are a far greater priority for the tank. Also any BoP synthweaving we should be aware of, considering that we're never going to do operations?
Yes, the reusable Biochem stuff still requires the appropriate level in Biochem to use. For Synthweaving, yes, there are certain pieces that are BoP, namely, any moddable Artifact-quality (purple) item you can learn to craft from schematics, and the Rakata belt and bracers. Other than that, you can make all kinds of other stuff to use or sell as you see fit (including augmentation kits and augmentations, Synthweaving makes augs for main stats like Strength).
Seeing as how you are not going to raid, you can still get at least the Rakata chest piece from completing HM Lost Island (probably will have to do it a few times until it drops your piece and you win the roll). You can get Black Hole gear/Columni gear fairly easily as well just from commendations. You'll be able to purchase at least the Campaign Armorings from the Black Hole vendor, and you can definitely purchase the Rakata/Campaign/Dread Guard quality mods/enhancements from other players. You can get Dread Guard/Campaign/Rakata relics, implants and earpieces from doing L50 Dailies quests and turning in the comms. So it's quite doable if you don't raid. It'll just take a bit longer and you'll need a fat pile of credits
BTW - if you are doing this as F2P, you'll need to both purchase the Equipment Authorization from the Cartel Shop to access Artifact-quality items.