For the solar cover, I'd look for one that comes cut to size and shape - some are delivered rectangular and you cut it yourself. I don't know if heavier plastic really makes them last longer, any thermal cover will suffer wear and tear and need to be replaced every so often. Color - I don't know if any color works better or worse, I bought blue because water is blue. 30' is pretty big, you may want to cut it into smaller pieces to facilitate handling.

Another thing to get - floaty toys!

Definitely get the K-2006. Much eaiser to read then other kits I've owned.