Softphone is a generic term for a phone, typically an IP phone, implemented as a software program or app running on a computer, tablet, phone etc.
Obihai have/had their Obion softphone app for PCs, Android and iOS. That can communicate with OBi ATAs and Obion softphones over the Obitalk network. Each account on the Obitalk portal gets one free 9 digit number to allocate to an Obion softphone.
As regards the question(s) in the 1) paragraph, yes.