The seal that allows oil onto the brakes is the one on the inside of the hub, large one in the top picture. Have a look at the surface the seal runs on on the stub axle. If worn significantly the stub axle will need to be replaced unless it is the earlier type with a replaceable ring, which it does not look like. If you do not replace it, expect the seal to work initially, but to fail early.
It is not necessary to replace any of the other seals, but probably a good idea to replace all of them. You need a new gasket between the free wheel hub and the hub.
The wheel bearing adjustment can be approximated without a dial gauge. It should be tight enough that free play is barely perceptible with the wheel on the hub, and does not provide any drag. First tighten until difficult to turn, then back off about 1/3 turn, tighten the locknut and check there is no resistance to turning, loosening a small amount at a time until there is none.
Bearings on Series 3 are oil lubricated from the swivel, but are greased on assembly for initial lubrication. (Series 1 had a plug on the drive flange so you could fill with oil for initial lubrication, this was dropped during Series 2 production.)
Check the bearings while you are at it, but being oil lubricated, they are probably perfectly OK.
It is considered bad practice to degrease brake shoes, as doing it effectively is virtually impossible. You need to replace brake shoes on both sides, and probably a good idea to replace the seal on the other side while you are at it.
1986 110 County 3.9 diesel
1970 2a 109 2.25 petrol