[RKDinOKC]

Dynamic dns will help you find each other's public IP by using a domain. You won't have to check your IPs before you try to log-in.

VPN usually requires server software on the hosting network, and client software on the remote computer. All traffic goes thru the server software, and the server will have to have a public IP, ie using the host router machine to give the VPN a public IP on your private network. And this will have to be done for each direction depending who is sending to whom.

You only need VPNs if accessing more than one computer on the other persons network or if you want the data encrytped when sending.

I have 4 computers with public IPs. They only have the services used turned on like web, mail, ftp, and my admin Apple Remote Access. Everything else is firewalled off. They have been setup like this without getting hacked for years.