Yes, one Hydrogen ion (actually one proton) has charge +1 and so two have charge +2.
That's good because that way "2 H2" has charge +4 while an Oxygen ion has charge -2 so that O2 has charge -4.
I assume by "solve", you mean find the net ionic equations. My suggestion for that would be the half-reaction method.
This podcast that I used in school tells everything you need to know about redox reactions: https://docs.google.com/file/d/0Bw9U...ZvTmF0Mlk/edit