Well, with a group this is a bit out there. You can double up on a lot of things and save a lot of weight per person. But, a lot of scouts, especially 12-14 years old, never seem to learn that they have to carry every bit of gear the entire trip. Axes, large hunting knives, video games, etc often make up more than my base weight.
Anyway, tarps are fairly easy. Roughly 7'6" x9' set up in a variety of configurations. These are a skill item. A larger tarp, around 10×10 will basically cover two scouts no matter what weather. These can be purchased from Oware or the like. Or, you can have a sew session. Learning to make a flat seam sewing a few loops (bar tack, "Z" stitch) is not complicated. Have some extra needles and bobbins handy. A few usable sewing machines is all that is really needed…most troups can come up with a couple. DIY.
Nests or bivies are more complicated, but not out of line. Perhaps a simple draped bug nest with staking loops 6" from the edges will work. Again, lots of designs from simple tarp tents with perimiter netting to full nests with bath-tub floors and doors. Draped netting works OK, but you will not be dealing with clouds of black-fies or mosquitos either. An easy DIY project for minimal funds. Or, these could be purchased from Go-Lite or Integral Designs.
Check the directions for hiking staffs. You may need to join the group to see the directions, though. http://f1.grp.yahoofs.com/v1/YAJ7T_zjvtAIUvAWNj38D2RAgVpa8r_mqARQO8XVBo2oO3c-wmxOyeiDexGSSRo0pbp5B4razi4sEA6Xow/A-HikingStaff/UL%20Trek%20Poles%20Cheap.pdf
CCF pads are good for scouts. For a bit more money I would recommend the NightLite pads from Gossamer Gear. Generally warmer, a bit more comfortable and lighter.
I cannot fault your choice of bags. A fairly good, low quality down starter bag that is quite inexpensive. But, I believe they quit producing this one. You may have to check around to get something different in down.
Check Gossmaer Gear for light, inexpensive packs. I believe the G4 is around $120-130. With a little modification to the CCF pads (cut and duct tape) they will fit into the pad holders, adding to the frame. Good volume if you cannot find a down bag, too. Generally speaking, of course, you *might* be able to get a small discount with a troup.
All will need a cup, of course. Every two scouts will need some sort of stove, usually a cnaister or WG. A 1.5L pot, as wide as you can get is good for two people at a time.