Sorry for the late reply. The EZ lube hubs are great for keeping up with already packed hubs. I would not recommend using them for packing your hubs.
I typically repack the hubs on my trailer every three or four years. I also give the EZ hubs a squirt of grease a couple times a year.
When I do repack the bearings I always rerplace the rear seal. I typically buy all may trailer parts from trailer parts superstore.
http://www.easternmarine.com/?gclid=...FUsXHwodPbkARQ
Tractor supply and any of the other stores you mentioned will have the seal. Pull the old one off when you go to the store to math it up.
Breaks: Check to see if they are working prior to pulling it apart. If they are working then pull the rotor off and look at all the break parts. If they are not worn out or falling off, you are good to go. If anything is bad above replace the entire assembly. (Trailer parts superstore) is your friend.
A quick look over of your tires. Trailer tires for whatever reason tend to dry rot quick and come apart. Make sure they are good to go. Make sure you have a good spare. I typically bring two spares on the long distant trip.
Looking forward to the trip. GETRDUN