The 4.7 is a good boat, a 60hp would be good match for it. Gel Coat chips are not hard to repair and if you get
Rib Shops Rib revive you can get a rid of a lot of the tube fading.
Yes you can add a bench seat, (there are numerous post on here about that).
As to the price, that is subjective, in the range £3-6k? it depends on what you are prepared to pay. If you google/ebay others on a similar type and size.