1. When is LN expected to be implemented? Given the current state of the network, this has to be priority number 1 for the Bitcoin Core devs. So a concrete date or at least a rough estimate should be on the table. Not "some time in 2018".
Bitcoin Core developers have been against increasing the mempool for years. Why would they want to support Lightning Network? Core devs are not the ones developing LN, so they have nothing to do with its release.
LN may not be the solution that you're looking for. In theory, it sounds great, but that just means that we now have a payment channel that not only we have to trust, but one that has to trust us that we won't be looking for exploits and bugs in the system. Additionally, LN goes against the peer-to-peer nature of the blockchain, and ultimately becomes a centralized second-layer off-chain platform for Bitcoin. My biggest concern with LN is that the only types of companies that are large enough or have enough capital to provide a level of trust for these channels are... well, banks and exchanges. So if you trust banks and exchanges, then by all means, have fun using LN.
All in all, LN is going to happen, but BTC Core devs have nothing to do with its implementation or development.