i don't know about the feats you may want for that build, but about the dip, you may:
-go for ShadowDancer, it gives you Hips first level, woull help you take advantage of your roguish side + makes it sure, they hit your familiar (to get the -2 malus) first while you're hiding.
-go for warblade (just a dip here too): gets you like 4/5 Maneuvers + one stance. Since any 2 lvls in a class count as 1CL in order to check the lvl of Maneuvers you can get, it's a great dip at later lvls. (
BUT, imo, one of the best feats in the game lol, is the "Weapon Aptitude" you get from this dip. Basically, it allows you to use any weapon feat (imp.crit, w.focus etc ..) for other weapons as well. (you have w.focus/imp.crit in short sword, then you found a good rapier, you can use w.apptitude to make the 2 feats work for the rapier O.O)