As I recall the starter kit from Lazy Days has a sewer hose and a potable water hose - the salesman should be able to give you the exact contents. I think it is a 20 foot hose and you can use it until it springs a leak, which will probably be within 3 months. A better quality hose (thicker material) can be purchased now or later. You will also want one of those multi-adapters for the end that goes into the campground sewer pipe. The multi-adapter fits 2 two different thread sizes as well as threadless pipes . With the threadless connections you will also need a rubber "donut" to seal the connection.
The Expedition will have an air system on the chassis and you might inqure about getting a tee installed (or appropriate connectors if already there) and an air hose to inflate your tires. However, a small portable compressor (the "tankless" variety) is a straight-forward purchase from a local store (e.g Walmart) and you always have 110V "mains" power available to run it via your generator. Just make sure its max pressure is at least equal to your standard tire pressure, which may be anywhere from 75-110 psi depending on the tires installed and the coach weight.
And definitely a good quality tire gauge, I like the electronic ones with a digital readout (again, make sure to reads high enough for your tire pressure). Sears stores have decent ones at reasonable prices - think I paid $15 for mine during a sale. Auto parts stores should have them too. You might also want to carry a basic tool kit (screw drivers, pliers, etc.). Wlamarts, KMarts, Sears, etc. has packaged kits for as low as $25 and as high as you want to go, depending on your handyman neds and skills.
A collapsible long handled washing brush is pretty much a necessity to wash the rig sides/windows. About $12-15 at a Walmart and maybe a bit more for an "RV" model at the Camping World store. I would also suggest an extendable handle windshield cleaning tool - the kind with a nylon scrub pad on one side and a rubber squeegee blade on the other. Bugs have an affinity for motorhome windshields and cleaning the windshield is a daily affair in many areas.
A step ladder can be handy for some chores but a 2-3 step stool is probaly sufficient for the odd use. A folding ladder is fairly expensive ($100+) and still somewhat bulky to store. Some of us carry a standard stepladder slung on a rack on the back of the coach. And you can usually borrow a ladder in a campgrond if something special comes up.
A good flash light is always handy to have.
You will undoubtedly need a 50 amp-to-30 amp adapter, often referred to as a "dogbone". This allows you to plug your RV's 50A power cable into a 30A outlet. Qute a few campgrounds either won't have 50A power service or may not have 50A outlets on the site you want (or the only site available!). Most of us carry a 20-25 foot main power extension cord as well. The 30A capacity cord is reasonably priced and modest in size, but the 50A cord is over $100 and bulky besides. A 30A extension is a reasonable trade-off between cost and capability. The 50A cord is great if you use it a lot, but expensive if you only need it a couple times a year. Depends on what sort of campgrounds you frequent.
Comfortable folding lawn chairs are a must for sitting outdoors on social occasions. Camping World will have several models, usually expensive and not notable superior to any other. Local stores (Walmart again) are a better source but selection may be limited at this time of year. You can always pick up some a bit later when the approaching spring brings a stock of chairs to every sort of store in the land.
If you are interested in outdoor cooking, a portable gas BBQ grill is recommended. The kind that uses disposable 1 lb LPG bottles is convenient for most uses. Prices range from $25 to well over $100. They all work and choice depends on your wants and expertise as a chef. Again, check the local stores.
Most of this stuff can be picked up as you go along. The tire gauge, the sewer hose connector, and the 50A/30A adapter are probaly all you absolutely need before you drive away from Lazy Days. Check the tire pressure BEFORE you drive the first time - do not assume it is set correctly by the dealer or factory. Of course, that means you have to learn what the corect pressure is - a topic for another thread, I think.