What charge would an ionized oxygen atom have?

Oxygen has 8 electrons
This means its electronic structure will be 2.6
So it has 6 electrons in its outer shell which means it needs to GAIN 2 electrons so it is stable
Once it gains the 2 electrons, it will have a charge of 2- because it has gained 2 electrons and electrons are negatively charged.

So an ionised oxygen atom will have a charge of 2-

Velocity is the speed of an object in a certain direction so you'd need to know speed and direction