Transaction on-chain can be predictable if only you understand how miners incentives transaction.
No, they are not. You are just being stupid. It has nothing to do with fees. Sometimes there is no block at all for 1 or 1.5 hours. No amount of fees can change that.
Why do you even need to use lightening network if you are going to be doing a one time transaction. Using a channel, you are going to open a channel which need an onchain transaction fee. Instead of doing that, why not pay the fee you are avoiding and have your Bitcoin confirm within some minutes. If you pay good fee, you should get your transaction confirmed in 10 minutes on average.
False assumptions. Like many other wallets, I have a lightning wallet always ready. I don't need to open any channels. Dumbass.