Hi, m0nkeybl1tz, and welcome to the boards and of course to this great game!
You should definitively have a look at the
Oolite Wiki, and there I would recommend especially three pages to you to start with:
The
FAQ-page will answer some general questions many people came across. So you may have them, too.
The
Ships-page gives information about all the ships out there, first the original, built-in ships, then OXP-ships. Each entry is linked to a (more or less) brief description of that ship, and, in the case of OXP-ships, to a download location as well. And yes, most of the built-in ships are purchasable for the player, provided you have the money. Have you read the ReadMe-file that came with the game, in order to find out where to find the shipyard in each station? The
FAQ will point you to some other instruction manuals as well.
The
Missions-page informs you about all available missions, again built-in first and OXPs later, the latter with links to where to find them.
Generally: You can easily start with no OXPs installed at all. No problem with that. There are however some goodies, and some missions for the yet unexperienced commander in OXPs that have been programmed for training purposes (like Long Way Around, Black Baron or Spyhunter). They all take place in Galaxy 1, so it is advisable to install and play them
before your first intergalactic jump.
Note, however, that all missions, built-in and OXP, will trigger only if certain conditions are fulfilled: Mostly you will need a certain standing (read: killcount), sometimes a certain amount of money, and sometimes you will have to be at the right place as well. So they are not very common in the Ooniverse. (When I started playing Elite on a C64 it took ages before my first mission screen popped up. I was
so excited, because I was damn sure I had seen it all.)
Finally, there is only one thing to add: Have fun playing!