Hi Robin,
Welcome to the Phoenix Cruiser family.
It seems that in some cases, what you think is a problem, is actually considered normal or have relatively simple solutions. zolman offers some great tips. Try your best to follow his suggestions. I will elaborate on a few of them.
About your concern of steering wander.
You say you bought a 2011 model 2551. You did not mention miles on the odometer. Unfortunately a brand new Ford chassis has loose steering. A chassis with 40,000 miles will wander worse. You either get used to it, or like us, you can invest is a few things to help reduce the floating feel.
One thing you have going for you is that model 2551 and model 2552 are two of the best PC models for lesser wandering. Having a 2011 Ford chassis means your front and rear stabilizer bars are decent, not perfect, but better than 2007 and older. Your bars might require adjusting to eliminate play that may have developed over the miles driven.
Assuming some of your steering handling is wear and tear, you might need new shock absorbers and a better steering stabilizer. We have heavy duty Bilstein shocks and a Safe-T-Plus steering stabilizer which helps the wandering a lot. You might also need a front wheel alignment.
One very important factor is making sure to put in the proper amount of air in your tires. You won't know how much air is required until after you weigh your rig. But there should be a Phoenix-provided tire pressure sticker inside the driver door. Start with the numbers they recommend until you get your rig weighed when on a trip. Too much air increases wander. Too little air reduces fuel economy and increases the chance for a tire blow-out. Tire pressure is a serious matter with every motor home, regardless of make or model.
Following zolman's tips, you should be able to plug into your main house, a 110v/15a outlet as long as you don't power up your air conditioner. I recommend using your PC-supplied yellow cord and a simple 30a-to-15a adapter. Walmart sells them for under $10. Here is a picture of it. This eliminates all concern of using an extension cord that is too thin of a gauge, and/or is too long. If your yellow PC cord is too short, buy a 30a extension cord, also sold at Walmart.

Here is a nicer one, sold at Home Depot. I like it because of the 90 degree 15a connection. It hangs down properly from the main house wall outlet, less chance of disconnecting on it's own.

Here is a basic 30a extension cord.

Using the right cords on a 15a circuit at home, you just might be able to use your a/c unit, but not with the microwave working at the same time. Get the basics working, then test from that point. But it starts with the right power cords.
I don't recall if a 2011 has a Tripp-Lite whole house inverter, or the next generation Xantrax or whatever. In either case, when plugged in, make sure the inverter/converter is turned on to maintain your batteries as well as supply 12V power to all your 12V operations in your PC.
Our 2007 has the typical crank-up roof top TV antenna and it sure is difficult capturing free air waves, so I feel your pain. I added this contraption called a Winegard Wingman to our Winegard antenna which is supposed to improve picture quality. Because we camp in remote locations, most often with "obstacle interference" we won't bother fussing with antenna TV. We do love to watch DVD movies. If we stay a while near a line-of-sight city, we will attempt antenna TV.
Since you also have a satellite dish, follow zolman's suggestions regarding a switch of some sort.

Regarding your back-up monitor, I think zolman is incorrect. In 2011, I believe the backup monitor is in the dash board radio and is simply not working. If you are missing the radio, then you are surly missing the monitor.
One thing certain. This is the best place to hang out and get your PC questions answered. Get familiar with this forum. It will be worth your effort.