Welcome to my world! Rusty bits if metal and seized components
Right, going by your pics of the chassis plate and brakes, I reckon you've got a Satellite model 252S. Have a shoofty at this and see if it looks familiar:
RSA Trailers spare parts : Launching types 212 à 342/S
And here's a break-down of the braking components:
RSA Trailers spare parts : SAV moyeux et freins GKN-FAD
Trust this is the sort of info you are after?
Agreed, your brakes are buggered, but the bearings don't look too bad. To clean them and grease them isn't too difficult. Pull them out (to get that back one out you'll need to prise that seal off). Clean the old grease out of the hub, degrease the bearings, then re-pack with grease and re-install.
Have a look at this previous link - scroll down to the 'how to change a set of taper roller bearings' post and that'll have pics on how to pack a set of bearings with grease.
Hope this is the sort of info you're after. All the best.