lurv

Here's a good starting point
https://www.tutorialspoint.com/csharp/
You'll be learning C# from various different sources, whether they be guides, video tutorials, asking questions on stackoverflow, reading questions on stackoverflow or simply asking a friend.
You should be taking time learning the very basics before jumping ahead and wanting to try things like making games and screwing around with source projects, learning the basics and syntax of C# is very easy and fun and doesn't take very long.

Nope

You don't have to create a new project to stop using hamachi. To use your own ip, you have to do something called port forwarding, which is letting players connect to a server hosted on your machine through a port (Intersect uses port 4000 I think but you can change that too)
 
Go here if you want to see what your external IP is, after that you have to open an exception in your firewall settings for the port you want to use, you can find tutorials on how to do that on google, but usually it's pretty easy, you normally type 192.168.0.1 in your browser's URL bar and get to your routers login page where you have to log in(it's different login details depending on the router and ISP) and then you have to go into firewall settings and make an exception for the port you want to use.

You can't do this with the event system. Event spells only trigger common events for yourself and what you're trying to do is impossible with only the event system.
When the source code comes out you could make a follower system or pay someone to do it for you

In the event editor, in the drop down menu for event trigger, select "Autorun". You can then select the "Wait..." command and put it to 10 seconds to repeat whatever you want. This will repeat an event every 10 seconds in a map, or if you want, check the "Global" option at the top to repeat it for everyone on the server.
 
Autorun makes it so that the event automatically triggers as long as you're in the map of the event.
You can do the same thing if you'd like the trigger to be action button/walk over but using labels to hop back before the Wait command.