Mark,
I bought a 1 inch belt for mine but haven't used it yet. Eric gave me some pointers
to look out for, somewhere on my HPE page. I don't really think it's necessary for a standard engine,
and fouling is possible unless you pay attention to certain items.
Yes, change the tensioner bearing, real easy, and readily available (3205-A-ZRS1TN9/HT33 from RS)
No special tools required. Plenty of guidance on here.
Bonnet cables: Prone to issues, to avoid breaking the vent grille for access, I fitted riv-nuts and screws
to allow easy access.
I use 10/60 oil from Mannol.
You may find a date marked on the battery. I would change it anyway. Varta D59 is good.
Nigel