Personally, it is not easy to get along with two male cats. A man and a woman can become husband and wife.
Even after sterilization, you will still retain a little bit of the true color of a male cat. 100% It is impossible to change your orientation.
As for where to do sterilization, it is not clear. If you want to be safe, don't have an injection. Castration will avoid future troubles and is more effective than injection.