ATC SCM7 vs. Proac Studio 110

ATC will prefer more power and will have a more articulate tight and punchy
bass (no port) but it won't have as much bass extension as the Proac (reflex
ported). The ATC midrange and articulation will have the edge on Proac but the
Proac bass extension and efficiency will have the edge on the ATC. The Proac
will probably be a lot more fun (small speaker big sound) but the ATC will be
slightly more transparent and better mids. Take your pick.

So with the close wall positioning, the bottom octave of the ATCs will fill in quite nicely without boominess.

I agree - the roll off on a sealed box is less steep - so ultimately you can get some useful deep bass compared to the risk of "one-note" bass that sometimes comes with small efficient ported designs.

Easy one - just ask ATC - send an email to the link on their website.

The cabinets on the new models do indeed look lower in cost to assemble than the older (German) cabinets. ATC make the drivers in house in the UK. They have always outsourced cabinet making - their strength is in engineering, designing transducers and manufacturing them - not wood work.