Thornblom, if you already have those two rifles and have found some matches to shoot, your first question seems a little strange...my suggestion would be to continue to shoot the CPA and low-wall at the matches, see what works for your there, and as you find additional accessories (and yes, additional guns) that you just can't do without, add them to your growing list of stuff you haul around. Regardless, you ARE started in the schuetzen game whether you know it or not (didn't hurt a bit, did it?
) and now the only things you can do are keep reading this forum (along with all related literature you can lay your hands on) shoot every match you possibly can and get together with whichever fellow shooters are local (and you define local) and practice saying, "but darling, we NEED this rifle now and it's such a great deal...the rent can wait 'til next month." There is NO cure, thornblum...you're hooked.
As far as specific improvements to your equipment, the sky is the limit (for instance I would think about a rimfire barrel and block assembly for the CPA so I could take advantage or that fine trigger in both venues, but the low-wall can be given acceptable trigger performance a couple of ways.) Other than that, just shoot as often as you can, keeping records of your sight settings in various wind conditions, etc. If possible find someone at the matches you attend who you can practice with so you can encourage each other and critique problems...it will surprise you how quickly you will progress.
Finally, be sure and look over things like Competition Corner in the Journal as well as other sources of technique suggestions. Try them in practice (or at matches if you must) and keep what works for you...we all have little "tricks" that we depend on, sometimes without even realizing it. That's why the more we shoot and concentrate on what we are doing, the faster we progress.
HTH, I guess I got a little windy, but that's what I do!
Froggie