Hi Vito,
I can't help with advice on leaks from that particular joint but I can on how to remove the inboard drive couplings.
All I use is a simple drift, and in my case that is a 1/4" diameter steel bar which I have crudely turned down to match the diameter of the roll pins for approximately the last 1/2" or so of it's length. Once you have the pins moving and they have cleared one side of the drive coupling then the rest should come out quite easily.
Before you start dismantling, check that the end-float on the output shafts is zero or thereabouts (I think 0.005" is allowed ?) If it is in specification, make sure to label the shims for both driveshafts so you don't get them mixed up. If you have excessive end float, then you'll need more shims for replacement, they are generally available from engineering suppliers and not "Lotus only" parts. The roll pins are reusable but again they are cheap so I tend to replace with new ones.
Brian