i wouldn't remove clips from key points... the plant will re-shape itself even if seeminly woody and set in place "now" ...
the net can work for that too, but the clips already exist and doing a good job.. take off at end.
low or high enough depends on your tent's heiht and how easily you can water -- automated and you can use the net as low as you want, almost...
unless you know it's a short stretch, i'd suggest continuin to use the net to keep the plant growing horizontalle for 5-7 days after flipping to 12/12... if you know they are big stretchers, go till 7-10 dys after flip befoer letting it all grow vertically.
Also, toward end you may let some stuff start to grow vertically while still weaving taller stuff to break apical dominance...
those last few days really try to even out the growth.. delay the stronger stuff, let the weaker stuff gain dominance for a bit etc etc... not all training has to be permanent.. may just want to tie somethin down for a day... or may just top somethin near a corner to get 2 vertical colas in that space -- it'll slow down for a sec andlet other stuff nearby catch up too. manipulate the plant to get the shape you want.