Hey canary5,
Welcome to the community and thanks for taking the time to post here on the forums.
1. Yes the engineer will be able to install extensions without cabling running between.
2. If you purchase a cordless phone that has more than one handset that would work perfectly, as long as the main base unit was plugged into the hub and the other handsets could then be placed in any room.
I can arrange the engineers appointment from here but would need to confirm a few details via a private message, that I will drop over in a moment. Please look out for the private message and we can get started.
Kind Regards,
Steven_L