Is it possible with the IPK to add admin ports/extensions besides the default first two ports (100,101) or at least change them if only two are available?
You can change extension number to port number in 4-10
There is a way to program from any port, but NEC does not recommend it, like SAT all programming does not take. The best way without issues is to program on the first 2 ports.
It is a class of service feature
You can program from ANY display phone on the Elite 48/192 and IPK.
Additional sets can be set to be "admin" phones in prog 4=17