I am so very happy to hear that you are getting another kitty. A boy is going to be a good choice, I think. A smaller one will seem less threatening to Blueberry, but a bigger/older one can successfuly be introduced also. Just look at their personality traits and you will know which one is meant for you.
I would definitely get a 2nd carrier. You never know when they might have to travel at the same time and confining 2 to one carrier is not a terribly good idea.
A 2nd and possibly even a 3rd litter box is also in order. Separate food dishes is also preferrable as they may not wish to eat together especially at first.
Make your introductions SLOWLY!!!! if you rush it, you might experience problems. And first impressions are lasting. And trust me, it might take longer than a week, but the wait will be worth it in the end.
Be prepared to keep new kitty by himself at first. It is more comforting for the newbie to have a single small room to get used to before an entire big house, new people and other pets all at the same time.
And most importantly.........KEEP US POSTED !!!! we want to see and hear everything!