Welcome to the world of RVing. Its not complicated and you will learn as you go. As far as necessities go, get a GOOD sewer hose like a Rhino Flex and a clear fitting to use to see if the tanks are emptying adequately. If you have a tank rinse connection get a dedicated grey colored hose to use with the tank rinser. A white colored hose for your fresh water connection and NEVER mix the two for contamination concerns. Emptying the tanks does not have to be messy, just never open a valve if not connected to a dump point.
Chocks, get adequate and proper chocks and never unhitch without first having placed them under the tires. The first time you unhook on an unlevel surface...even if it looks fairly level, and the trailer moves you will learn your lesson. Been there, done that, won't happen again.
Good advice on camping in the driveway a few nights at first, then find a state park or campground fairly close to home for the first couple of outings. Its better to find out if things are working properly close to home than be half way accross the country if you need to take it back to your dealer. Getting warranty work done is a whole other experience.
Remember to give yourself more following distance when towing. Be defensive and slow down and enjoy your travels.