previous posters must have missed that this is a shed roof, no ridge,
so no ridge vent and no ridge cap. go ahead and put drip edge on.
when you get to the top, cut the top of the shingles off and just use
the bottom half with the colored granules on it. if it works out that
you need just, say, and inch of colored shingle, then you will have to
make a judgement call about what looks best; the little strip or a bit
or black showing or an oddball row. nails will have to be exposed when
fastening this last row, but cover the nail heads with a small dab of
roofing cement (available in caulk tubes--one small tube will do it) if
you'd like. (bet you it doesn't leak even if you omit the tar).