yes wall thickness matters, a thin wall can collapse under vacuum. Why not just take a handle full of your lines down to your local auto parts store match them up and buy a few feet of each size you need?

To make it a little easier, you can use the Larson kit.

Here's a link: http://www.roadraceengineering.com/nwdsm_larsonhosehasitsownpagenow.htm

Maybe I was just sloppy, but when I had the yellow silicone vacuum lines, they liked to hold on to black dirt/grease. For me, they were hard to keep clean. Now, I like black rubber lines - much easier to keep clean. Just sharing my experience...

Most don't care, but silicone hose is not suited for crank case venting. Any silocone lines that carry oil vapor will allow oil to bleed/leech through the hose. It will however still hold vacuum.