I couldn't order Infinity as my D/L speed was predicted as <15Mbps. However, I opted for the 'With Fibre' option and am getting reliable (very reliable) D/L of around 25Mbps.
I don't D/L that much, but my 'Option 3' is unlimited (subject to fair use, etc).
BT / OR will need to install their Modem and you will need to connect that to their (your) Home Hub with the supplied Ethernet cable (I think mine is around 2 Metres long). I assume you are talking about an Infinity FTTC connection.
Both Modem and Hub need a Power connection. However, from the Master Socket they can fit a 'Data Extension Cable' of up to 30 Metres in length, so your Modem can connect on the end of this in a suitable location.
Allergy Advice: This post may contain traces of Meerkats.