I want to build a house with steel. I'm interested in building like say 8' wide exterior walls, with staggered studs or double 3' studs to prevent thermal bridging; is this feasible? Are the studs going to be secure enough only screwed to the top and bottom channel from just one side?
Nope on all accounts, since it seems you're talking about big store steel studs. You would need to have Structural Steel Studs & they aren't store bought & must be part of a submitted, approved & continuously inspected building design. After all that, then most definitely yes on all accounts.