Derailer adjustment
 

So I have read many of the threads on this and have a few questions left.

1. It seems that I cannot adjust the B screw on my rear derailer to get it to stop hitting the cassete. In the largest gear in the back and the smallest gear on the front it rubs the cassete and cannot be turned in any more, it is all the way in.

2. Does someone have a picture on the correct height to mount the front derailer? I think mine may be too high. Or is there a good procedure for this?

1. It's possible your chain is too long for the gear combination you have. Shift the bike into the big chainring-biggest cog combination and see if the rear derailleur cage is nearly straight in line with the chain. If there is noticable slack, the chain should be shortened until you can just shift into this combination safely.

2. The bottom edge of the front derailleur cage should clear the big chainring teeth by 2-3 mm (~1/8") Be careful how you do this as modern chainrings have a few shorter teeth as part of the shifting enhancements. Use the tallest teeth as your guide. I've heard that a nickel (~2 mm thick) makes a good clearance guage but I just set mine by eye.

How can you adjust this while leaving the cable attached and the cage over the top ring? My cable runs under the bottom braket and when I losen the band it pulls down.

You can't. You would need to adjust the cable tension after moving it anyway. Just loosen the cable anchor bolt, adjust the derailleur height, and re-set the cable tension (see park tools or sheldon brown websites for setup instructions).

There is also a nice video here: http://bicycletutor.com/adjust-rear-derailleur/

Which DER and what size is the cog?
If you are using a DER designed for a max cog of 28 and trying to use a 32-34, toy;ll have problems.

Longer screw might help?