The wise choice was getting rid of that Defender. The Bounty Hunters would have been all over you.

The Cavalier is the best light fighter you can get at this point in the game. If you're more into heavy fighters, most battleships in the region should sell the Crusader. There's also the Wolfhound which you can buy at a Molly or Rogue base.

The only thing you HAVE to do is make some money. How you do that, is up to you. Some people prefer trading, others taking missions.

Well what weapons should I buy? Are the ones I currently have sufficient?

Usually, the ones that are considerd "max energy" on the best ship you can buy at any level you are at at the time, are what you want to have when you continue on to the next level. In other words, if you can buy that nifty/extremely UGLY Britonian heavy fighter, see what the max rating is on the guns. That should give you some idea as to what weapons to get.
Also, remember. If you take missions, you are slowly becomming enemies with one faction or another. Usually, several at once. So if you go that route, keep an eye on your rep. It gets frustrating if you go through a jumop gate, just to be killed befor you can do anything because you have 30,000,000 enemy on the other side, that will target you first, even though thier worst hated enemy is right next to them.
The easiest way to build money is to trade. If you need the protection of the heavy fighter to do things, you still get some cargo space. It's slow, but safer.