Ooooo, how exciting!! Pics please, when you can!
I think it's a great idea to introduce them on neutral non-home territory, that's wonderful. As far as adjustment, we got Marcel when Wylie was about 1.5yrs old, and at first Wylie was a little confused -- he became more needy/anxious for about a month and we just supported him through that time...giving him lots of extra love and attention and he adjusted just fine. Then when we got Pfeiffer, both the boys were just all "okay whatevs, no biggie".