Welcome aboard Bit Buhkit and Gray Lensman!!
Make generous use of the tutorials, especially the navigation one and the torpedo targeting one. With both of these, you can try different things and get used to the simulation's controls. Start a career with the idea that it's a tutorial, gradually ramp up the difficulty as you're comfortable.
Best to experiment with the different mods and find a setup that you like. I use TMO and RSRDC with other minor mods. Be sure to read the documentation that comes with the mods. Some are incompatible with others.
There are different thoughts on when to start adding mods. Some say start them right away. Some say play the game vanilla, then add the mods. That way you can appreciate the changes more. I say get some experience with vanilla, then start experimenting with the mods.
Don't be afraid to ask questions. We're all glad to help, and won't make fun of you too much until we know you.
I'm the self appointed, unofficial assigner of jobs here at Subsim.
I have a special job for the both of you. The headlights need changing and it's a two man job.