Using several brokers for diversification will help you to smooth out the overall result. BUT: all these brokers need to have good trading conditions during the night. Write me personally if you need specific advice on that

Most of the parameters are already close to optimal values. It is preferred to use default values for most parameters (except the 'Symbols separated by comma' and lot-sizing related parameters)

EURUSD, GBPUSD and EURCHF are the most liquid pairs with the least slippage, night scalping usually works best on these pairs. Additional diversification across multiple pairs might help a bit in case of small lot sizes or might not help you at all (especially with significant lot sizes). Based on the Occam's razor it is better to trade only a few best pairs, not trying to involve additional diversification for little gain

The VPS choice hardly matters in case of Night Hunter Pro, as it uses pending orders. Pending order is executed on the broker side, so it's essentially like having 0 ms latency all the time, no matter what VPS you use. You might as well have 2000 ms latency with your VPS, it won't matter and execution will always be on the broker side due to the use of pending orders

If you want to not have trades held over weekends, you need to set 'Hour to Stop Trading (on Friday)' to 22. This way EA won't open new trades at Friday and won't have trades held over weekends

If you want to use several instances of the EA on one account (for example, to use your own optimised set files with different pairs, timing, SL levels, etc.) you need to have unique UID number for every copy of the EA! Otherwise different instances of the EA will conflict with one another. For example, first set file can have UID = 0, second one a have UID = 1 and so on

If you get "Failed to get MODE_MARGINREQUIRED" error and it's there multiple times it means one of the following:

You either got some of the symbols wrong (e.g. haven't added suffix)

Or you haven't shown symbols you would like to trade in the Market Watch

Or you listed symbols in the 'Symbols separated by comma' parameter using wrong delimiter (for example, a dot or some other symbol instead of a comma)

Some brokers might restrict having pending orders too close to the current price, effectively restricting any scalping this way. Most brokers do not use such option, as it is mostly used by small brokers working against its own clients, but you can check if your broker has something like this (picture "Stops_Level" below)