Definately get him neutored. Even after the op as his hormones remain high, he will continue to hump, mine did it for about 4 weeks, but iv heard of others doing it for a few months.
Id say keep him seperate from her until hes been done and for 2 weeks, then gradually start introducing them, through bars at first as he'll still be hormonal, then start giving them time together. I found this to work fine for my buns, aslong as he doesnt continously chase her. Mine used to be fine for 5 mins, and as time went on was fine for longer, so i followed his hormonal pattern really. And now they are playing together fine- just waiting to finish converting the shed before they will live together properly. Good luck