Hi and
1) Yes the Home hub is also a wireless router.
2)THe hub phone is for making VOIP calls. It charges from the Home Hub
3) The free calls are made using the phone you get. It routes calls over the internet so they are cheaper, but you still use it like a normal phone.
4) As for install/setup times you would need to ask BT. Or check the site you linked to in your post as it has lots of frequently asked questions and info on set up and all the hardware you get.
Steve