How to set up Lightning Network conf file. RPC user / password? and zmqpubraw? In my lnd.conf file I have the following settings:

debuglevel=info
listen=192.168.100.134 
externalip=186.4.235.84    
alias=MyNodeAlias
color=#000000
maxpendingchannels=5
bitcoin.mainnet=1
bitcoin.active=1
bitcoin.node=bitcoind
bitcoind.rpcuser=bitcoind_rpc_user_string
bitcoind.rpcpass=bitcoind_rpc_password_string
bitcoind.zmqpubrawblock=tcp://127.0.0.1:18501
bitcoind.zmqpubrawtx=tcp://127.0.0.1:18502


What is rpcuser and rpcpass? which values should I use? Also, what is zmqpubrawblock and zmqpubrawtx?
So in Bitcoind you can define authentication via an rpc interface (remote procedure call). In the config file of Bitcoind which is usually located in ~/.bitcoin/bitcoin.conf you can set the values for

rpcuser=bitcoind_rpc_user_string
rpcpass=bitcoind_rpc_password_string


Obviously you should select other values than the ones in this answer / question. You could also pass those values as command line arguments to Bitcoind. 

As for the other two values. Bitcoind uses zero message queue (zmq) to share raw block data and raw transactionsdata. I guess raw means binary (but I am not sure). These two values are the zmq sockets for both interfaces I guess they are pub / sub sockets to which your lnd node will subscribe.