Imho it's a one-time operation and you basically just leave it running. I know that people don't have enough patience though. I don't know how good or bad it performs as node though.
Quite bad from my personal experience.
This is the part where I can tell "please don't count on that". Since off-chain can bring the heavy load, I think that it's normal for on-chain remain restricted (may need a better word here, I am thinking at block size only, no other restriction) and expensive. If we don't do that we may end up with miners leaving when the block rewards get too small.
You can introduce some form of scarcity, but only up to a point. Afterwhich, the benefits start to taper off and you're better off increasing the block size to increase both the capacity of the network as well as to help the miners increase their income. Being on ~4vMB blocks for the near future is absolutely not okay and it should not be an option at all. You do need on-chain transactions for second-layer solution. It is impossible to support them without having on-chain transactions, for opening/closing channels for example.