I've two kegs ready for conversion. How many couplers should I weld with to start? I am thinking one for a ball valve ond one for a thermometer to start on each.
Personally, I would take the time to lay out what you really want out of your brewery. Once you have a design you are happy with, then start building towards it. That way you won't be pissed three months from now when you wish you had positioned your couplings differently.
I am a planning freak, but check out my build thread for some ideas of how to design and think through your brewery.