Wecome to the forums and Hobies in general!
1. From the photos, the mainsail only appears to have 5 battens (unless I'm mistaken) from the pics on these forums of other user's boats, I understand that the traditional number is 6?
The original Hobie 14 sail had 5 battens. The design was changed in the early '80s so that the battens could be placed on the panel seams (easier to make), which resulted in the 6 batten main. The performance difference is marginal, with the 6 batten main being slightly faster.
2. In some hobies, the battens are angled on the mainsail and in others, some are straight. Does this make any difference?
No. I think what you are seeing is the difference between the 5-batten sail (where the battens are angled to the panels) and the 6-batten sail (where the battens are on the panel seams).
3. The jib seems strangely wrinkled... As it has no battens in it I am guessing that the jib is supposed to be self furling, but could not see any trace of a furler on this boat?
Unfortunately, the boat is no longer listed, so I can't look to see what's going on. On a 14T, the furler is pretty obvious at the jib tack.
4. Also, the jib appears to actually be attached to the forestay (rather than on a separate halyard). Is this common? Without the halyard system, how would one take the jib down mid-trip without having to beach and dismantle?
On the OEM 14T jib, the luff wire is the forestay. There was no way to remove the jib without dropping the mast. There have been a few workarounds - a jib snorkel cover, hoisted by the main halyard to protect the jib from the weather (no modifications needed) or having a luff zipper sewn into the luff of the jib (separate forestay) that would allow you to rig a halyard system similar to either the 16 (cleat on the mast) or the 18 (inside the jib luff pocket w/ a cleat at the jib tack).
5. I cant see any trapeze system on this boat and thought that the H14T came with a trap as standard. Perhaps this boat is actually a H14 which has been modified with a dolphin striker and a jib?
Could be. There were a number of "unofficial" turbo conversion kits before Hobie Cat formally introduced the Turbo in the early '80s. If the boat is older than ~1982 this is almost certainly the case.
Thank you very much in advance.
No worries, mate!