On Tue, 25 Jun 2013 22:43:53 +0000 (UTC), "Danny D."
wrote:

3. The "runners?" appear to be 1/4" or even less in OD.
http://www3.picturepush.com/photo/a/...g/13410571.jpg

I follow the notion to use fewer 1/4" tubes in the 1/2" poly. The
more holes you pierce in the 1/2" adds to potential leaks. It cuts
water flow a bit, but the tube drip heads can be adjusted to
compensate. Or run it longer on the timer.

The 1/4" can be "teed off" the main drip line with barbed fittings.
Easier to fix than a 1/2" pipe with 10 holes in it.

I put in my front yard (desert) a manifold. Tubes run from it.

http://ecx.images-amazon.com/images/I/41HoeIZg0eL.jpg

Each line can be adjusted for water flow.

Given your small space I bet the manifold (4 port) would be best.

I forget if the manifold is threaded into an old sprinkler head tee.
You get the idea.