1) yes, this is the problem. "Chromium" is Chromium metal, Cr NOT the ion, likewise Nickel is Ni, etc.
2) You can give the charge for each part, that's fine, and even write them seperately as this will make it easier to spot the spectator ions.
eg. Lithium dropped into aqueous HBr
HBr(aq) <-----> H+(aq) + Br-(aq)
Li(s) + H+(aq) + Br-(aq) -----> LiBr(aq) + 1/2H2(g)
But,
LiBr(aq) <-----> Li+(aq) + Br-(aq)
So overall,
Li(s) + H+(aq) + Br-(aq) -----> Li+(aq) + Br-(aq) + 1/2H2(g)
So Bromide is a spectator ion, and the net ionic equation is
Li(s) + H+(aq) -----> Li+(aq) + 1/2H2(g)