taking 1st trip end of the week got questions
Actually, before you take your 1st trip, you should go stay in a campground near your home for a few days. This will let you know right off what you are missing, and you can just go home (or to the store) and get it... Also, allows you to make sure everything works.
Most important are hook up things. Water hose (white) - at least 1 25', and 1 or 2 25' and a 10' would be better. An inline pressure regulator is manditory, and an inline water filter is very useful. It is a good idea to have a selection of right angle/45 angle/flexible adapters to allow hooking to some of the weird water taps out there without kinking your hose. Electrical adapters so you can plug into the 3 common services out there, 15 amp/30 amp/50 amp. At least 25' of electrical cord built into the trailer, and a matching 25' extention cord is nice. Some power services are not very reliable, so power conditioning/surge protection can be useful, but pricey. A plug in power line monitor is cheaper and will at least let you know if there is a problem.
Sewer hose, at least 2 10' sections, the heaviest duty you can get. A clear adapter tube or angle so you can monitor the dumping process, a good angle adapter to connect the other end to the dump site, a way to carry the hose(s) and parts after use, and rubber gloves. Some people carry a spray bottle of disinfectant. Eventually, you will need to worry about cleaning the tanks, but that can wait until you have some experiance.
Next is set up stuff. This includes ways to level and stabilize the unit if these are not built in. Options include various jacks, ramps, blocks and chocks.
Next, 'fill it up'. Propane tanks, some water in the main tank (depends on where you are going, because transporting water costs money - 1/4 tank seems a good choice unless the trip is long or there won't be any available at your destination), chemicals in the toilet if you use them (along with refills), septic friendly toilet paper, food, condiments, plates/cups/napkins/silverware (plastic/paper will do), towels, dishcloth (if needed), paper towels, cooking necessities, matches or lighter, good flashlight with extra batteries, fire extinguisher(s), soap.
And your personal stuff.