Welcome to the forum and thanks for starting the thread. We have our 312 for a couple of years.... and still getting the bugs out.
Axle and hub problems
Fresh water tank self draining problems.
The factory does not fill the spindle and hub cavity with axle grease. 'Manuel' says to pull hubs and repack bearing once a year(do it or 'your warranty' on your axles are voided). I would jack you tires off the ground and pull them in and out to make sure that the bearings/castle nut are tight. Also the carter key in the spindle is about as cheap as they come and will/may break.
My trailer brakes are self adjusting when braking -GOING FORWARD-. See if you have this style and check them and back them off when need be.
I had to get a Thin Wall Socket to be able to take the wheels off, as a 4-way will not work.
Fresh water tank would self siphon out more of the water at the breather tube so I installed a shut off valve and open it up when set up at camp.
Keep an eye on your tires, I have D rated tires that came with the unit and on 'china bomb' exploded with about 200 miles on it after I bought it. I now have two spares with me at all times. I installed one of these BAL - Innovative Products for the RV Industry
Learn how to use the over ride controls
on your slides outs. When you have a jam up you will want to know how to get them in/out. My slide would go out ok, but coming in, the 'slide' would tilt down and drag too hard on the rollers on the floor under the slide. Found out that the in wall carriage would kick out at the bottom and push out the outside panel and loosened the outside screws that kept the Assembly in the wall. Ended up drilling a few more screw holes and put in some heavier screws to stop the movement on the main slide.
The outside kitchen door (up/down) was jamming and found out that the screws holding it along the top were not heavy enough to hold it up and they will work out.
The inside kitchen faucet looks nice, but it is cheap junk that will leak badly everywhere. Replace it with a home one that you like from Home Depot/Lowes/etc.
You will want to put scissor jacks under it, as the 'stabilizers' too little to nothing in stabilizing it or holding it up (gets a lot of weight off the electric jack when camping with the scissor jacks). I use quick release plates (save a jack) and pull the jacks off when going down the road.
I also have a canopy hold down kit and poles from "OC".
Awning hold down poles.
Also get a surge protector.