Let's say that I have a channel opened and I want to send some lightning BTC to someone who didn't ever used lightning, is it possible or will it be? Or will I need to open a channel first then send the btc through lighthing(with 2 transactions)?
I know the guys from Raiden want to allow that: https://medium.com/@raiden_network/creating-an-easy-onboarding-user-experience-for-the-raiden-network-4dcdc9e2eeed
There is no such thing like 'lightning BTC'. It is the same BTC, either on-chain, or comitted to a lightning channel, which is technically a 2 of 2 multisig transaction. To receive via lightning, a lightning full node or a wallet with lightning receive capability is needed. And correct, you need to open a channel first, which takes one on-chain commit, the the associated waiting time. But it is possible to transfer value at the same time by already assigning a portion of the channel funds to the receiver when setting up the 2 of 2 multisig transaction. All later value transfers inside the channel will be an just update of this transaction, which will be instantaneous. So either way, no need for a second transaction in terms of on-chain transaction. Except for the closure of the channel, if needed - which will another on-chain transaction ( channels can stay open indefinitely, though).
You can use the wallet c-lighitning for sent bicoin to a simple wallet bitcoin with this command
lightning-cli withdraw <pubkey> <shatoshi>
But you can not use the your channel, the satoshi that you use for sent bitcoin to simple wallet bitcoin are separated by the channel
