Do a search for 'Manzella Neutral Grip' - Brian has a PDF teaching the grip. It's also taught very well in both Building Blocks and the NSA videos. For me, Brian's teaching of the neutral grip where the back of the left hand monitors the clubface is absolutely the most important starting point for everything Brian teaches. A lot of folks around here experiment with stronger grips, and there are certainly reasons to do so. But I think that until you learn to rotate the sweetspot off the plane in the downswing and to lag it to the ball (monitoring pp#3), that it's a really good idea to be using only the Manzella grip (which is really just the Hogan grip turned a tiny bit to the right, or the Tiger Woods grip, etc. - but Brian teaches it extremely well, with a TGM emphasis on PP#3 that you won't get in Hogan's book).
I've never heard Brian say anything about number of knuckles showing, but for me a Manzella Neutral Grip is a '2 Knuckle' grip - 3 would definitely be too strong and 1 or fewer would be too weak.
I can't say for certain, but your grip sounds extremely weak.