Battery megastore on line for the battery, about £98 delivered. 1000CCA 135AH.
The blue aerial wire is under the plastic in the rear quarter that the parcel shelf fits to.
Alternator should have a regulator set point of 14.2 volts or up to 14..8 volts.
Just mind that the alternators are different on gems and thor engines. If you have a large plenum stamped 4.6 it's a gems engine. If your engine has a set of banana shaped manifolds on top it's a thor/Bosch engine.