Blue Protoman said:
If I open a port, can someone hack into the router and see what I'm doing?
In theory. There needs to be something exploitable on that port though.
Blue Protoman said:
Well, how can I do remote administration on Pandora and have it be secure, then?
Having a port open is like installing a door or window into your house: best you can do is include a good lock with the installation and trust that the lock maker designed it to be difficult to open without the key.
In general, computer locks are pretty secure. At the very least it takes no small amount of time to hack a computer with some reasonable security on it. Combine that with the fact that no one really cares about what you do (I'm assuming no one would really care what you do, they're primarily focused on big companies where there's more challenge and payoff) and you should be able to rest easy in your relative safety.
You can do things to increase your security further. There's "honeypots": fake ports designed to be easily hacked but still look like a real computer on the other side to make the hacker think there's nothing there; non-standard ports, the computer equivalent of installing a secret passage under your house that only you know about unless the hacker spends a lot of time looking for it. There are third party programs you can install that will monitor your open ports and will send alerts if it notices any activity: sometimes it'll just be you logging in, but that one time you were in class and you get an alert...
The media likes to spread fear of "hackers", but most of the security breaches I've seen recently were companies not doing what they should have, or employees doing something they shouldn't have. Never plug an unknown USB stick into your computer, for example.