°waits til all the other 2054 members had their go
and goes making new tea°
Ooh, I seem to have forgotten to add my 2p!
Here it is: your best option is to download an existing OXP that more or less does at least part of whatever you want to do, then have a look at the wiki, hoping to see the relevant section. If you don't fancy reading the wiki at all, do ask in the forum something like: I'd like to make a ship/system/station/Oolite component do this & that, how do I do it?
If you really want to do some proper modding, it's definitely worth having a good look at the wiki. The documentation there is not perfect, but at least it should give you a general impression of all that could be done. I personally find that a quick read through will help figure things out a few days later, when suddenly everything will kind of start falling into place...
Hopefully that tea is ready by now!
And now for something slightly different: you might have noticed some similarity in all the answers. It's basically because the question was... well... 'big' for lack of a better word...
Still, have you got a 'smaller' question to ask? All of us could conceivably write a list of what is possible, but it would take ages to do, since at least 90% of everything you see amd do in game can be changed one way or another. (Sneak preview: at least 95% - well, it seems like 98% to me, but let's err on the side of caution - will be moddable in 1.74 when we release it!
Whose turn is it next?
PS & plug: my farsun oxp is one of the smallest ones around, load it, look inside it, and see how it does its stuff to get a feel of what needs to be done when changing the way the game works. Or maybe look inside a replacement sounds oxp, for a different - and actually simpler - style of modding.