Young Gun help needed

I'm new to the game and have been playing as a Young Gun for a few days. I'm just not earning much money with a scout and a medium miner, making me think that it's going to take me hours and hours for me to build up a small fleet that can get me enough credits to start running a real business.

I've been searching online and trying out their techniques, but maybe some of y'all can help me with these questions:

My one-star captain on my miner is just slow af and sometimes just sits around in an asteroid field that my resource beacon shows has much content. I can fill my 10000 m^3 hold in no time if I just kick him to the curb and do my own drilling. Should I spend time to up his star rating? I want a competent ship that I can put into a repeat loop that will generate, say, 500k every 20 minutes. I will add more miners after that.

There's a dearth of stations that purchase a lot of ore or silicon, especially near good deposits. Is there a mod that allows me to up the demand? It's too sparse for me to enjoy playing much longer like this.

If I purchase a DLC, can I add the new systems to my current save and continue on w/o the storyline (until I'm ready for it)? Maybe more sectors will get me better ROI of time.

Thanks, friends!!