So I started a new character (level boosted to 70) and jumped straight in to Onslaught. Obviously this auto-completed content like KotFE, but if I were to start Rise of the Hutt Cartel now, would it cause any potential issues with companions or story progress?

If you could actually initiate these, i.e. sending a flirty message to a companion who you potentially missed a romance option with - it could actually prove to be a workaround that would re-open, or initiate a romance?

I can't be the only person who feels like between the story segments, their romanced NPC essentially just isn't interested. Throughout the story, both Theron and Lana make a pretty outright case for needing a vacation, and it'd be lovely to actually be able to give that to them (or at the bare minimum, a date night)! At time allotted intervals, you'd receive mail from your companion mentioning a break - or an evening off, launching this would then transport you to them where they'd say they want to spend some time with you. Different options could include a weekend in a cabin on Alderaan, a meal at a cantina, having them believe they're being sent on a mission (when it's in fact a secretly organized picnic), a night at the sith opera.etc Going through the mini-events would then improve your relationship, and potentially reward customization options like "Casual Lana" or "Lake Vacation Theron". Because really, who doesn't want to see their favourite Sith in sweats, and Theron in an unbuttoned Hawaiian Shirt.

Vaylin's armor has been a huge want for me, especially as it has a hood with hair.

I recently messed up the Lana Beniko romance and decided to start a second sith inquisitor on sorcerer rather than an assassin. Looking at their chapter progress though, it's showing as 'completed' for the story arc of Fallen Empire? If I continue with the character, will it remember the relationship choices made on the other toon - and subsequently block the flirt options again when progressing?

So I started playing around three weeks ago, subscribed, worked through the first two expansions (flirting with Lana throughout Shadow of Revan) - and (as I'm sure a lot of other people have) locked myself out of the Lana Beniko relationship by not flirting when the camera is on Theron... Honestly, from this point on I've actually just lost interest in continuing the story. Being able to quit a conversation and re-do it is one thing, but not actually realizing what you're doing and subsequently ruining a playthrough for yourself is another. I'd even happily reset my character to the point they were in the story (gear, credits.etc) just to be able to fix the mistake. I really hope that the option to go back and change decisions, or even reset the story to that chapter becomes available - but until then I think I'm probably done with SWTOR.