Overall PAI usage is very similar to Bitcoin, the RPC layer is the same and the P2P is very similar differing only in the protocol specifics like genesis hash, magic bytes, address formats, etc.
###P2P Ports:
8567 - Mainnet
18567 - Testnet
19567 - Regtest
###Default RPC Ports
8566 - Mainnet
18566 - Testnet
19566 - Regtest
In order to interact with paicoind via RPC, you can use any of the same tools that work with Bitcoin. In this example we use bitcoinrpc (https://github.com/jgarzik/python-bitcoinrpc) which is a simple wrapper layer to the standard Bitcoin RPC. All of the expected RPC requests are still present and can be seen with paicoin-cli help.
Please refer to python_rpc/simple.py for this example. You can use the included requirements.txt file to get python-bitcoinrpc installed via pip.
For peer-to-peer usage and Java we have modified bitcoinj to fit the requirements of PAI, including all of the various network settings. The repository: https://github.com/projectpai/bitcoinj/tree/paicoin on the paicoin branch contains this project as well as a new module called pai-demo which has a usage example with extensive comments. In general though, anything that can be achieved with the standard bitcoinj should also be possible with this modified version as the only relevant changes are in the NetworkParams section.
Please refer to the README here: https://github.com/projectpai/bitcoinj/blob/paicoin/paidemo/src/main/java/com/oben/README.md