Thanks for the great (no pun intended) answer. Is this a "norm" for an organist looking for "bigger sounds"?

Looking to upgrade organ from stock organ software. Is it a waste to order software for 3 manuals if I only have 2

2 basic questions about the computer I am using at church: 1. Is a new MacBook Pro recommended and should I use 3 screens?
2. Can I switch computers without having to buy Hauptwerk V6 or better again?

Thanks Much! Dale