We looked really hard at that model before deciding to trade in the 2280BH for a 2104S. The Rockwood bunkends were supposed to be able to take upwards of 800 lbs. and ours never showed any signs of problems at all over the two years we've had it. I can't recall looking at the shower setup in the 296 other than to know it's got a hard sided bathroom...if the shower curtain setup is like ours was, it's just got a rail that's roof mounted and it just pulls around the shower section. As for the screen room....it may depend on the brand you get, but I assume it's Dometic to match the awnings they put on them. If that's the case then, yes, the fasteners along the bottom (and maybe the sides / roof ) have to be screwed in. From the pics I've seen, they don't really look out of place and not that difficult to install.
2012 Chevy Tahoe LTZ - HD tow package
2017 Rockwood 2703WS Emerald Edition