The public tx key is contained in the extra field. You can use monero-utils-deserialize to decode it from the transaction's hexadecimal representation, which you can get from the daemon, like this:
print_tx TXID +hex
(replace TXID with your transaction's txid)
Then, in a shell:
monero-utils-deserialize --input DATA
(replace data with ...
You need to run a private testnet. Instructions can be found here: https://github.com/moneroexamples/private-testnet
Without it being private, your mined blocks wont make it onto the real testnet chain because you are mining with a lowered difficulty due to you using the --fixed-difficulty 10 option, and they wont get broadcast due to you using the --...