Here's the magic site again
Drum Tuning Bible
This page can give you run down on how different shell wood types and heads will affect the sound of your kit, also check out the tuning and seating section. That should solve your echo problem.
Now, for a good value, double-bass pedal, I can thoroughly recomend the sonor 400 series. I've been using it for sometime now and it's a very versatile pedal. However, pretty much anything on the market will hold up a long time, so get to your local store and try them (and anything else you ever buy) out first.
Which brings me to my next point, the "20 china. Are you certain you want one? I only ask because I once desperately wanted a big china, but once I actually got my "22 2002, I was more than a little disapointed. I thought it was going to give me a short, low-pitched smash, but the physics of these things means they do ring for a long time. But my "18 alpha has been marvelous, so I counter with the "22 like a gong. Again, just try it out first.