That's exactly what the pass thru outs are for. The input jacks on the two speakers you mention are combo jacks that can accept both 1/4" TRS/TS cables and XLR cables, so there's no need for oddball cables.
Mono is fine...it's vocals that should sound the same to all parts of the theatre. If the speakers I listed have 1/4" inputs and a 3-pin output, I assume I would just need to adapt the XLR back to 1/4" before it goes to the next speaker?
EDIT: Just saw Drew's response, and I didn't even notice that the inputs were combo ports. So I can go XLR from my board all the way through the system? That would be ideal
XLR and TRS should both be balanced ... the difference would be that XLR can carry phantom power (to powercondenser mics) and TRS does not ... but you aren't using mic inputs here so I don't think it matters.
Please note, if you are using LR as a two channel mix in any way (either panning inputs to favor L or R or using a stereo track as input to a stereo channel), then you should try to send a mono mix to those speakers.