The others are correct, there is no rear main seal, nor is there a seal in the front of the gearbox. It is very common to see oil where you describe and unless you are willing to do a butt load of work, it won't get better. It is, however, not the cause of the low pressure, since thats most likely bearing wear and/or to low a viscocity of oil. I would change it to get rid of the barrs leaks stuff ASAP. I have a personal distaste for oil additives.
The problem with the rear leak is that any oil supplied to the rear main bearing, oozes out of the bearing towards the front and the rear as its supposed to. The oil that goes to the front just dribbles down into the pan. The oil that goes to the rear goes into a radial channel with a slinger and has an oil retun hole at the bottom, maybe 5/16 " in diameter. The most common flaw in this setup is that the joint that exists between the rear main bearing cap and the block is supposed to have a sealant on it (Hylomar jointing compound, I think). I have never pulled down an A series engine that had a trace of any. Under oil pressure (70psi cold) oil is not only supplied to the bearing, but also forces its way between the cap and the block. The pan gasket, weak as it is, will not stop it. You can replace the pan gasket and slow it down and it may not leak initially, but it will within a few days.
I hear you saying to yourself, HA, I'll just pull the motor and seal up that cap...and it will stop that leak, but the first time you warm it up and accellerate hard, most of the oil in the pan sloshes to the back of the pan and restricts the return hole in the rear bearing cap so some oil does escape out the very rear of the motor because the slinger is now overwhelmed. The slinger works great as long as you don't actually drive it. You can Idle in the driveway all day and never seep a drop.
There is a rear main seal kit for Spridgets and I have one, but the backs of the cranks are all a little different and I had to pull my motor 3 times to get it to stop. The seal is 10mm thick and I only had 9mm of crank. I had to partially install the seal and have 2 mm machined off of the flywheel boss. to get it to work. In retrospect, I'd be just as happy to live with the leak, for all the trouble it was.
Brakes sticking can be caused by a plugged return hole in the MC, or not enough pedal/MC clearance, or a swollen flex line (swollen internally). With disk, the seals in the caliper can swell with age, or the inside of the caliper body can corrode causing a mechanical bind with the pistons. Drum cylinders can suffer from this corrosion issue too. The test as to which one it is is a simple as cracking the bleeder valve. If the brakes free up when the valve is cracked (it will spurt a small amount of fluid), then the problem is in the fluid return to the MC. If the brake does not free up when you do this, then the caipers need an overhaul or replacement.
Best of luck ... and welcome to the joyful world of owning an old car :)
-Michael