1. You can run several wallets on a RPi. It's depending on how RAM consuming the wallets are. You can also use an old desktop machine for this purpose but check the power consumption. Every kWh consumed because of old/inefficient hardware is a loss.
2. It's depending on how powerfull your machine is and how many wallets you want to run.
3. Any that is supported by the wallet(s). You have to be comfortable with it (e.g. compiling in linux is not that easy for me). If you are comfortable with windows 7/10, use it! Almost every coin offers a wallet version for windows.
4. There is no need for several fixed IPs you need one only. Even with 1 IP you can run several masternodes of the same coin (you have to use different ports).
Thanks a lot for the answer. One last question please :2. It's depending on how powerfull your machine is and how many wallets you want to run.
3. Any that is supported by the wallet(s). You have to be comfortable with it (e.g. compiling in linux is not that easy for me). If you are comfortable with windows 7/10, use it! Almost every coin offers a wallet version for windows.
4. There is no need for several fixed IPs you need one only. Even with 1 IP you can run several masternodes of the same coin (you have to use different ports).
If I buy a VPN, I won't have to worry about masternodes bandwidth right ? (I don't know much about VPNs) as some say that masternodes will consume 100-500gb per month which is lot more for me. Does internet speed matters or is it like mining a rig(runs good on low speed but stable connection).
