You will be able to create separate alerts for every level or create one for price crossing any level.
Because of some TradingView limitations, alerts won't be fired for the first bar of the session. Will try to solve that in the new versions.
In the script used new v4 plotting features, so will be able to plot levels and labels nicely. Unfortunately, there is a limit on the number of consecutive lines you can plot on the plot (around 50), so lines in the past will disappear.
Past performance does not guarantee future results.