The foam may be coming from a few different things. Length of line, Over carbonated, (and believe it or not) not opening the tap all the way.
Lenght of Line is dependant on the temps and types of beer being served, A good average is about 6 feet.
When my kegs get overcarbed, I bleed the pressure to almost nil and then pour a beer. Leave it off the bottle for as long as it takes to undo the issue. Then put it back on the bottle. I have been thinking about getting a multiple head unit for my kegerator in order to vary the pressure on the different styles of beer that are in there. Stouts need different pressures than lagers and other ales.
I use Cobra tap's (Picnic tap's) and I find that when someone new steps up to pour a beer, they don't open the tap all the way. Then they wonder why they got a glass full of Foam. Don't be afraid of the tap, It wont explode unless you are doing something seriously wrong.
Cheers
Preston