Can somebody help me answer that or have experience with it?
1. It depends if your EAs are well coded to work together. There is no optimal, maximum is limited by computer resources only.
2. Limited only by your VPS available resources (RAM, CPU, HDD).
Almost the same question:
Can i run the same EA with different parameters and on defferent currency pair (on the same opened MT5)??
Maybe yes, maybe no. Unless the EA has been coded with this in mind there is the risk that the EAs might interfere with each other by managing the trades for the other EA.
So yes, you can run the same EA twice or more, will they work correctly ? that depends on the design of the EA.