2 questions about setting up VPNs...

Hello guys! So in the process of settuing up my own virtualization software, I came across two questions I had about setting up a VPN to connect to my virtualization servers over the internet (and other great uses that a VPN enables). So here they are:

1. How powerful does a VM need to be to run a VPN server for a few people to use opver the internet? Specifically ram and cpu. I am wondering this because I am thinking of outsourcing the VPN to a place like vultr, digital ocean, buyvm, or amazon ec2 to have that server managed on its own. That way I would not have to worry about taking down my VPN when I move to college in the fall. Edit: I see that people are using RPis for making the VPNs, could I use either this on the RPi, or this on a VPS?

2. What is the best operating system to install the vpn on? I was thinking of using either Ubuntu 16.04 (desktop, I am new to this stuff so I prefer having that option, but I am open to learning the command line more for this) or CentOS 7. Additionally, I am looking at using Pritunl (Edit: I think I would just use the openvpn script I mentioned in the first question, but I am open to options if you think that pritunl is better) since it seems very easy to setup (I can juist look up tutorials on how to use it I assum, again this will be my first real encounter with linux servers and VPNs).

Any help and insight into this would be greatly appreciated! Thanks!!!