question 1- Yes, they are notorius for eating shrimp, but size palys into this. Tiny shrimp like sexy or sarron are bad news. But larger cleaners are usually ok as long as the Psudo arent large.
Question 2- No. they are perfect model citizens when alone. Mix two dottys in a tank and as I said in a similar thread I think just yeasterday..........
Dottyback Thunderdome
Two dotty enta....One Dotty leave