You do not need to unlock Tia or Dacy, only Slime in Episode 4. Tia comes with Episode 4, Dacy with 5 I believe. And yes you do need to restart at level 1 for those characters, don't see why you wouldn't.
As for her attacks, a few of her hits are automatically multiple attacks, such as her first hit, and her 3rd A in AAA. Either it ends at AAA or AAAA, I forgot, but her A-spam string is short like Dainn's. Another hit of her's that is multiple attacks is her Dash S attack, which causes her to do a sliding kick that hits about 3 or 4 times if I remember right. I would need to play around on her again to check all this stuff for accuracy...but every time I play her I only wish we had her more
As for when we get her...someone who played on KLunia told me they got Tia and Episode 4 about 2 months after Open Beta started
so we shouldn't have to wait till October if they follow suit for GLunia. If anything we may get it a little sooner, hopefully.