running live and test node simultaneously
You can run both at the same time:

$ bitcoind -daemon
$ bitcoind -testnet -daemon


Then you can issue commands on either using:  

$ bitcoin-cli &lt;commmand&gt;


or

$ bitcoin-cli -testnet &lt;command&gt;


The blockchains are stored in ./bitcoin/blocks for mainnet and /bitcoin/testnet3/blocks for testnet.

Update: With the bitcoin.conf updated in the question remove rpcport=8332, so it doesn't try to use the same port for mainnet and testnet RPC.

Update 2: With 0.17 release, it is now possible for a single configuration file to set different options for different networks in bitcoin.conf:

main.uacomment=bitcoin
test.uacomment=bitcoin-testnet
regtest.uacomment=regtest


For more information, see the 0.17.0 Release Notes