There are two ports used by nodeos, p2p connection (9876) and http connection (8888).
You can change them by adding options when you execute nodeos like:
nodeos --p2p-listen-endpoint=0.0.0.0:9876 --http-server-address=0.0.0.0:8888
change number ...
the problem is coming from beforeEach function => you are deploying each time a new contract and it throws, because you are creating your user only in the first test suite
Replace beforeEach with before
Create a user in each of your tests
You'll find the scripts for building eosio in the scripts-folder.
$ cd scripts
to build eosio.
follow this guide to Build from Shell Scripts
or this guide to install prebuild binaries