Goodness. You're asking an awful lot in one short post!
Welcome to the GPF - this forum is an incredible source of information. I would say at this point in your planning you've got the cart way ahead of the horse. 7 koi in an aquarium? You're gonna need a much bigger pond.
I'd recommend you start reading some of the pond construction threads and figure out what it is you need to know. Asking for someone to tell you how to build a pond is far less effective than you reading what's already been shared. Once you've put some time in reading and learning on your own, your questions will be more helpful for both you and us.