The thing that annoys me is that Font of Inspiration is most useful at low levels, but the higher level you are, the more you'll get from taking it again. So I get locked into a vicious cycle of taking it every time...
As for the feats mentioned, I think whisper gnome makes an absolutely killer factotum character if your DM agrees to swap gnome thingamahammer familiarity for the quickrazor, since it fits the iajutsu theme so perfectly. Item Familiar can be good, but it's kind of a questionable feat since it's UA material. Don't forget Mindsight along with a level of Mindbender for lots of fun.
I like Knowledge Devotion, but the factotum always seems so strapped for feats...I guess if you're working in cleric levels though, cloistered cleric would make a killer choice.
JJ's handbook, by the way, has some errors in it that were never edited out, like how their spell-like abilities can't fuel reserve feats. It would certainly be a good project for somebody to pick up and complete.