1) There's more than one way to do this. A method that I've used is to add a small file to the client computer that uses the "onFirstWindowOpen" trigger in File | Options to perform a script everytime the file is opened. This script can use Open File to open the file on the server. When you specify the file to open with this step, you can click the remote button and locate a file on your server to open.
2) You don't need VPN, but it is an option you'll want to evaluate. VPN can give you access to more resources on your network than a direct client to host connection from outside the network.
With the correct port opened through the firewall and port forwarding set up to forward requests on this port to your host computer, you can use Open Remote from outside the network if you specify the IP address of your internet router. This is the IP address you get if you use a web site such as WhatIsMyIP to see the router's external IP address rather than your host computer's internal IP address used on your local network. Note that you Router's IP address may change from time to time unless you get a static IP address from your internet service provider. There are also services you can use that can work around the need to get a static IP address.
Thank you I am going to try all that. point number 1 is clear and I think it iwill be easy to implement but point 2 is a bit more involved and I have to esperiment with it to find the best scenario because I have not done this before.