It's great that you are researching and learning before you bring the little dude home. You and he will be so happy because you will be all ready for him.
Goats are very social animals and need to be with other goats. You really need to have at least two goats together for them to happy and healthiest. Single goats get bored and can even have mental health issues due to the stress of not having a companion. Can you get another little one close to his age for him to have as a friend?
You said that he was weaned so you don't need to bottle feed him. How old is he?
You also said that you will have him fixed later? That means he's a buckling now? I highly suggest you have his owners band him or wether him now by some other means.
He needs a good quality hay, probably grass hay or a grass/alfalfa mix right now. I've not had wethers so I don't have the experience to give you good, solid advice in this are. Others here do though. Goats do much better with loose minerals as stated above. It's also best to leave out some baking soda in a container that they have ready access to if they get an upset tummy. They know when they need it.
I always encourage new people to spend some time on
http://fiascofarm.com/ website. Lots of great help there.
Good luck, keep learning - you will love your goat(s)!