Once you give her the 3 items, she leave on a trip for one week or more, don't remember exactly the days, then you have to go back to her and she invite herself in your camp, that's how you can move her around.
They're also supposed to be a shade of green, you'd think that a smaller elf could exist in lore, I know it's because of game code limitations and to not make it too complicated, can't fault the team for that, but it's a bit a shame it does limit people's rp.
There's no consequences, you'll just get rid of the withdrawal, and yeah you have to defeat Jasvalla, she's pretty vulnerable to tease attack by the way, she can be defeated quickly like that.
You can remove the debuff by waiting a few days as long as you're not her official sub, just go to sleep until it go away, you can also temporarily put the game in easy for the fight if needed. Also you're talking about the pirate fight? You can resolve it without having sex with them if you...