The above is a starter kit from etrailer.com. (Get to know these folks,they have a great selection of gear) In reality you will probably have to double both the water hose and sewer hose lengths. An inline filter for the water as well as a pressure regulator (if the trailer did not come with one) are a good idea for the water hose.
For the electrical a EMS (electrical management system) aka "surge protector" is highly recommended.
As for your PDI (Pre delivery inspection), somewhere on this site or with a search you can find different lists specifying what to check prior to accepting the trailer.
My first trailer was at a dealer who had onsite RV parking. We hooked up everything and spent the night there. Turning on everything gas,electric and water (inside and out). Also gave me a chance to become familiar with correct set up of the trailer.
Just the beginning my friend.
Welcome to the fold and the forum.
Let go of your pride (mistakes will happen) and hang on to your wallet. RV adventures (and equipment) are not cheap.