Well, these don't look too bad. Info on how 10 or 13 points affect the probabilities isn't widely available, and I lack the means to run those numbers myself.

A quick EV run suggests that you need an 86% of each 13-pt teased game coming through for the teaser to be neutral EV. According to Tradesports, the odds of SF and Ind winning are a little better than 86%, so you could be in +EV territory if you were to tease those two favourites. That's pretty back-of-the-envelope though. Otherwise, I just wouldn't know which numbers to tease.

Again, I don't have enough research to be able to say either way. I'd just remind you of what I remind myself every time I construct a teaser, which is not that I'm teasing to a line that looks good, or that I'm more comfortable with; I'm aggressively teasing certain numbers that give me the increased probability necessary to make the game +EV.