> Excellent, I've been trying to figure this out; whether I will be able to just jump on/off using my debit (or Oyster) card as I currently do on the over/underground.

Note that you can also use contactless or Oyster on National Rail within the zones, e.g. King's Cross to Alexandra Palace or Moorgate to Finsbury Park.

> Any idea how far out of town this ticketing system will be usable? Will someone in Reading be able to use a contactless card without having to buy a paper ticket?

At the moment no. One would hope that common sense will prevail.

People will be able to use contactless and oyster once the Reading side of the system is taken over by TfL in a year or so.

If I recall correctly, this is already the case on the other side of Crossrail (Shenfield/Brentford). It's also been introduced at Gatwick Airport recently.

You recall correctly - the Shenfield part has been switched on for Oyster/contactless