1. Use Knossos - all in one installer, manager and launcher! https://fsnebula.org/knossos/
One nice thing is that it can extract everything it needs from a FS2 GoG installer, so you can not bother yourself with installing FS2 on its own.
2. This thread will be helpful for you: https://www.hard-light.net/forums/index.php?topic=80688.0
Of course, you can pick any mod on Knossos and play it. The mod list is constantly updated so any mod someone makes will be available to you in the Explore page. You also get notifications of new mod updates!
3. I have no idea about model work but there's definitely a program called PCS2. Perhaps you'd want to check it out.
And the most important, welcome and have fun!