You don't need a rooster to have eggs from the hens so I'd rehome him and get a second hen instead.
If the goal is eggs for eating, yes.
But if the original poster wants to hatch eggs and breed more chickens from this pair, then the rooster would be very necessary.
You should have nine hens to a rooster, that way he does not affect egg production and overall hen happiness.
It depends on the rooster.
Some people pen a rooster with one or a few hens for breeding purposes, and some of those are just fine. Some other people have large flocks (way more than 10 birds) with only a single rooster, and some of those hens are still over-mated.
The common guideline of 10 hens per rooster has nothing to do with keeping the roosters or the hens happy. It's a guideline for big commercial places that produce fertile eggs for hatching: they need at least 1 rooster per 10 hens to be sure the eggs are fertile.