Robert my best advice would be:
- Install SH3 Commander. It is not a mod, but rather an add on application that will not mess with other mods.
- Install freely new ship types
- Install the Harbour Traffic mod, or, even better the Unified Campaign for the "plain vanilla" game
Then play several missions without having to worry about new mods. I would also suggest to study the mods (sometimes inadequate) documentation, and see what you are interested in.
I wouldn't suggest to try to install all the mods you downloaded together, since some of the mods conflict with each other (especially old with new ones)
When you do that, after some missions, or even a whole career, you will be a experienced Kaleun and you will know by yourself in which direction to go (mod-wise).
And my last suggestion is to hang around the forums.
These guys here are the most helpful people I have ever "met".
I didn't say welcome Herr Kaleun!