Try to get trees about 12-15 feet apart, and get the ropes/straps at about a 30 degree angle from the hammock ends.

The taut ridge you describe is common to gathered end hammocks. Putting your feet to one side or the other and your head toward the other on the diagonal, and using a stuff sack as a knee pillow helps, as does getting the "hang" of finding the right amount of sag for your hammock.

Foam pads can be tricky. some like to make a hammock sleeve out of a neat sheet or nylon, and some silicon seam sealer dotted/streaked on the bottom of the pad will help keep it from slipping around. As will finding adequate sag to lay flat on the diagonal.

Check out hammockforums.net for tons more suggestions on this....