When will PRL go to mainnet (release wallet and change from token ERC20 to coin)?
DAGchain network is difficult to install and easy to hack. After the combination with blockchain would be better?
I'm not sure about the answer to second question, but I know that the mainnet is scheduled to be released in April. The team really honored their deadlines so I expect for them to honor this one too. It will probably be released closer to the end of April (at least that's how they released the testnet A and the testnet B).
No the ERC20 tokens are part of the protocol.