All easy stuff you could do yourself in a day maybe.

the synchro springs often break they look like a large c shaped spring x 2 ,baulk ring worn ,does it grate ,later baulk rings were coated and this sometimes wears off ,if you can remove rear seal collar and 8 x 10mm bi hex bolts fastening rear...

I’d be changing the stub axle seals as the oil that’s dripping looks like ep90

Maybe not enough room for you but on the Grenadier they mount the spare wheel the opposite way round and have a storage area in the wheel hollow.

I read it as they came down the section to the left of the waterfall going downhill, which is slightly less steep

My experience with terrafirma shocks and springs would say there no where near as good as ome stuff. Springs rust massively quick and shocks snap pins or leak fluid from new. Had 2 sets of terrafirma shocks replaced under warranty before ditching...

Just used rtv silicone on mine with no issues.