I would change the fluid first, if you have no prior history this has been done, needs doing ideally every 3 years.
If towing with it ?, it is in desperate need of a oil/air cooler, tbh they would last longer with one on even if not towing, I've had loads of auto's, gf is disabled so need auto for her, it's made a massive difference to my foot not getting cooked in my sierra auto on a long trip!!
There is a bit of a small lump between 1/2 gears especially when cold, it sounds like the revving issue could be a pressure problem, but hopefully yours has had all the mods done to the early ones to fix problems, most common of which was the clutch basket breaking up, the lump however could be caused by the sensor on the end of the gearbox, visible when looking underneath the front near side wheel arch, a two wire connector goes onto it.
This senses the turbine speed of the box, and they often go duff, easy to do in theory, in practice the sensor breaks off leaving half in the gearbox, they can be a royal b***h to do, my advice take the car to a auto specialist for them to drive, as it is much more accurate than chasing problems via someones description, this would be best, and let them do the sensor if needed, there are many many other things it could be, but all in all not a bad box as auto's go.
tabetha