Hi Jay,
Oil leaks ? it's a Lotus....
Ok, being serious minor leaks are common. Mine's a 352 box and when driven daily always had indications but not usually bad enough to form a drip under the car. After not using it for a few years I changed the oil and came back to find a pool underneath the car so had to change the seals. It's easy on a 352, not sure about the 365 but if it's a bad leak that does sound like a winter project.
Shim tensioning is mainly about stopping the in/out play between the driveshaft and gearbox, it shouldn't affect drag on the wheel itself (or at least it doesn't seem to on my car).
If your car is standard my first guess would be the rear drum brakes. It could either be because the handbrake cable is binding and partially holding the shoes against the drum, or simply that they've been adjusted too tightly with the shoes dragging. With an under dash handbrake going through a front lever then a horseshow splitter in the centre tunnel, it's got to be absolutely spot on to work well. So over-tight shoes is one way of getting an MoT pass mark - assuming the tester turns a blind eye to it !
The TCS should feel nippy although it's not fast compared with current sports cars such as the Elise/Evora/Porsche/etc. Even if you discount the period road tests as being fixed by Lotus with "special" engines, the cars should still be doing 7-8 seconds for 0-60 and feel good compared with most modern traffic.
When you say it's running hot, what numbers are you getting on the dial ?
Brian
(edited because I couldn't believe the number of typos I made first time around !)