DOUBLE BASS

I've read in various locations throughout these forums about the double bass option for sending full range to front speakers and then also sending the lower frequencies to the sub as well. I would like clarification on how to set up these possibilities for my combination of speakers and receiver (both with and without the double bass as I would like to try both if my system is capable).

***related question: LFE. I've read that this is simply a distinct channel in dolby/dts coding. How does this channel play into what the sub actually sees? i.e. during movie soundtracks how do the crossover settings interact with the content of the lfe channel and the other channels?

SURROUND CROSSOVER SETTINGS

I'm also not real sure how to handle my 422-C surrounds (yes I am using these center channels as surrounds). They are rated down to 100 Hz, but I'm not sure I want to send the sub any signals above 80 Hz. As they are surrounds, would it be possible, and would it have an obviously negative effect, to just send 100 Hz plus to the 422-C's and only send the 80Hz and below portion of the signal to the sub?

 fyi-my system:

2*632LR fronts

533VAC center

4*422-C surrounds

Bravus 10 D

Onkyo 705