a lot of what you may be looking for is going to rely on personal choice and flying/fighting style , I'd recomend going online and trying out your skills in an RPG enviroment. Many of us host servers mine for example is PG13, RPG if you read through the posts you'l find many mods and pure servers, try new things , and above all have fun, freelancer is a community as much as it may be a great game. You'll find both good and bad, try different loads on your ship, try new ships, you may be surprised at what is best for someone else may not be to your liking. I hope you enjoy and have a Blast.

Whether you spectate or participate,Life Happens

Once you've completed the story, you're basically free to do whatever you want. There's no more "motivation", so to speak. However, at a rough guess, you see about 15% of Sirius during the story. There's plenty more out there.

Vis a vis your equipment query, the best equipment you can have is not a fixed thing. Different people like different weapons. The general "best equipment" is usually 2 Tizona del Cids and 4 Nomad Blasters. Some people replace one of the del Cids with another gun, or a missile, but that's what I use and it does me fine.

Once you've finished exploring and found everything you want to/can be bothered to, it's generally time for one of two things - to get some mods to play, or to move online. Or, of course, a combination of the two, there are many modded servers out there.