what are the recomended freq/slope for xover?

The WP8's go down to 21Hz...not sure of the 7s but the normal THX crossover recommendation of 80 Hz is probably too high a cossover for your speakers. There are other things to consider like the low pass crossver of your surrounds and your room dynamics.

Without a sound equalizer like that found on the Velodyne DD series, you may have to play with the phase and polarity settings after picking a spot where the subwoofer sounds loudest and tight and also fits into your decor. Avoid somewhere in the center of the soundstage or room. A few feet from a wall or corner near one of the main speakers usually works best. Then experiment with phase and polarity settings to see if the bass gets louder and tighter. I suggest doing the above with the sub's crossover or (not both) your processor set at around 50 Hz given the low end capability of your WP7s.

You can then adjust volume so the bass blends in and so the sub doesn't draw attention to itself; it should seemlessly blend into the sound of the main speakers. Then go down 5-10Hz until you hit the low pass of the WP7's low pass of around 21-25Hz and listen for the best overall bass that is tight, not boomy and blends seemlessly into your main speakers sound.

that is sort of what i did. the surrounds frequency response is 45hz to 22khz and the center is 55 hz to 22khz. the theta crossover is set for front and center at 50 freq and 12 slope, surrounds 60/12. a theta guy who used to help me out had them set closer to 80/18 and l/r around 50/18.
i was just not sure of where/why the ideal settings are...

ironically, i actually prefer the sound of the sub where you suggested not to place it! i move back and forth but now it is centered. this is also thiels recommended placement for 2 chanl.

Have you played with the 2 other crossover type the casa nova has??

rleff- very little as they recommend phase perfect to be the better of the 3 for most situations.

I run soundlab m2's with martin logan stage center and paradigm studio 20 actives for rear,my sub is a passive chiro c150 driven by adcom 2535 bridged.
I found the linkwitz-riley with 18,24 slopes gave me the best sound and intregration;maybe you might want to setup all 3 types on 3 different input selects and then you can a/b them to see if you can hear improvement or not.

I ran soundlab m2's with martin logan stage center and paradigm studio 20 actives for rear,my sub is a passive chiro c150 driven by adcom 2535 bridged.
I found the linkwitz-riley with 18,24 slopes gave me the best sound and intregration;maybe you might want to setup all 3 types on 3 different input selects and then you can a/b them to see if you can hear improvement or not.