I agree with some of that. As far as costumes I think you have to go with these:
Here's a guy over at screen rant's idea some of which is good but I wouldn't kill one of the big five:
Here’s my personal vision for X-Men: First Class (in 3 acts):
Act 1: Real world setting and tone, modern teenagers trying to tackle the usual hardships like hair in strange new places; Ice and/or wings growing where there wasn’t any before; telepathic voices changing; and laser beams shooting uncontrollably from the eyes when excited. The kids parents freak, even going so far as to shun or abuse their children. (Seeing ‘the real world’ react to the sudden emergence of these ‘freaks’ would be a very interesting take on the X universe. People could really empathize with that.)
Act 2: In steps Charles Xavier with his long time compatriot, Erik Magnus Lensherr. The two build the school, (and the X-base beneath, Magnus’ idea, ‘just in case,’
as a haven for the emerging mutant populace. The first class is enrolled but are awkward with one another, unsure of themselves and their strange new powers. Xavier and Magnus, (in two subtly different ways,) help them conquer their insecurities and embrace their powers –even show them how to work as a team. However, just as the kids come into their own, intolerance and fear amongst normal humans bubbles over. One student pays the ultimate price. Magnus, broken-hearted and disillusioned, gets twisted into the militant terrorist, Magneto.
Act 3: Magneto tries to lure Xavier and the kids over to the dark side with him. Xavier refuses, causing an irrepairable rift in their friendship; the kids stand with Xavier’s ideals, Magneto mockingly dubbing them his “Xavier Men.” Big final battle: the kids manage to stop Magneto from doing any real damage, but another big price is paid: Xavier’s legs get crushed. In the aftermath, humans fear mutants more than ever; new mutants are either forced to, or choose to reveal themselves and be who they are; Xavier’s school welcomes those in need; the first class steps up to become the X-Men; all while Magneto sits lonely, recruiting help where he can, secretly missing the family at Xavier’s school he has abandoned.
Fox execs, I can have a full script ready in a month! (P.S. if my 3-act masterpiece should end up as the official script, remember your favorite neighborhood film clairvoyant over at Screen Rant called it first!)