User blog comment:PhineasxIsabella/Phineas and Ferb Trivia/@comment-2217944-20100801054859

ANSWERS:

1. True. He speaks Martian in "Unfair Science Fair Redux", though what he says is basically his line backwards. He speaks Japanese as one of his lines in SBTY.

2. Dan Povenmire's sister. Tiana, Linda's sister, is Dan's other sister and therefore she really is Linda's sister.

3. Clyde Flynn