JB,
It's ironic that I just finished going over battery types and uses in the Marine Electrical Systems class that I teach.
In general batteries can be designed to perform optimally for starting or deep cycle. A starting battery needs to put out a lot of current in a very short amount of time. Deep cycle batteries put out much less current over long periods of time.
Over the years battery manufacturers realized that many people that own boats use the same batteries for starting as well as deep cycle. Moreover, it is less expensive to stock one type of battery, rather than two. This is why starting/deep cycle batteries were designed. They are a compromise design that does not do either function as well as a dedicated battery can.
A true deep cycle battery would be the best thing for you to get. Failing that, go for a combination battery. The batteries will come in three sizes or groups: 24, 27, 31. Measure the battery compartment and get the largest size that you can fit in it.
As far as bearings, the standard recommendation is to repack them at 1-year or 10,000 miles, whichever comes first. Personally, I think the one year interval is way too short for properly sized bearings/axles. I've used 3-years and 10,000 miles on my previous travel trailer, as well as a motorcycle trailer without any issues. When I have them apart I carefully inspect the bearings and races, if there are signs of excessive wear or overheating I replace them.
A good thing to do when repacking bearings is to get all the part numbers and buy a spare set of bearings and seals to keep in the trailer in case of an emergency. I pack the spare bearings with grease and keep them in a sealed plastic food container. This way they are ready for use.
Article on bearings:
http://www.trailerlife.com/rv-traile...heel-bearings/