Guineas are indeed very vocal. They are much like children; vocalizing when they are happy, sad, lonely, scared,etc Adding another pig to the mix shouldn't make any difference... other than adding another voice to the mix.
Guineas on Yesterdays News can sometimes be an issue, watch to make sure your pig isn't eating/nibbling on it. If he is you should switch the bedding.
They cannot produce Vitamin C, just as we cannot. As a result, they can get Scurvy. I find it more reliable to purchase chewable Vit C tablets from your local pharmacy, crush them, and sprinkle about the equivalent to 1/4 of a tablet onto the food.
Fruits and veggies are great. Make sure you consult a list of what would be poisonous to your piggie, as there are a couple of things to avoid (Guineas are prone to bloat and the fruits and veggies fed to them can play a huge role in this). Another thing to note is too many fruits and veggies can cause diarrhea.
Guinea pig teeth are constantly growing. You should supply wood chew toys for him to wear them down on.
Keep in mind that they also need their toenails trimmed regularly... a lot of people tend to neglect that.
I think I answered the questions you had... plus added a couple important facts about Guineas... Hopefully that helps you out
He's a cute pig and I'm sure he'll grow on your husband