a bandpass will filter the HF and the LF. A normal box will only have HF filter, acoustic suspension (seal) or base reflex (ported). It's super hard to tune a bandpass, i don't recommend that unless u get a pro who know how to do that, which i doubt there are any here because 99% of the ppl here either do a ported or sealed box.

Pro: u get better bass in the bandpass frequency

Cons: frequency cut off below the bandpass frequency

you might want to try out the alpine active sub

something like this http://www.incarnow.co.uk/product_info.php?products_id=85

ok why not ok ? 1 amp will have 2 channels normally unless it's monoblock. So u can drive 1 channel per woofer.

brand is very subjective, u want head bang boom boom boom or nice sound quality bass ?