Another sandgroper here - welcome!
I own a Rockwell 6S. I would recommend it if:
- The asking price is within your comfort zone
- You want a "buy once, cry once" razor - a stainless razor is a lifetime purchase and this razor has cured me of the desire to buy or try any more razors
- You aren't likely to continue to try other razors (a 6S has most of the aggressiveness spectrum covered with its different plates although plate 6 isn't as aggressive as some razors). If you want to try a lot of different razors (open and closed comb, single edge, straight etc) then do that first with cheaper ones to work out what you like.
If you do buy a Rockwell, then I suggest starting on the lower plates (I start all my blades on plate 2 before increasing the aggressiveness as the blades wear in) to reduce the risk of harm. It's pretty difficult (though not impossible!) to hurt yourself on plate 2, even for a newbie. As you find the angle and improve your technique then you can go up to the higher plates, otherwise I find I stop getting close shaves after the first couple on that plate. As it is, even after a year of doing this, starting off a new blade with a high plate is a recipe for at least some damage, unless I'm concentrating on flawless technique (I just haven't got the patience for that long term). So just start on a lower plate and transition to the higher plates as the blade wears in. I get 10+ excellent BBS shaves per blade with no damage from this technique. There is enough variation just in trying new blades to keep you occupied for a few years...
As for brushes, I'm a boar fan and the king of boars for me is the Omega 48. You can treat it like you stole it and it's also a screaming bargain for newbies who want to dip their toes. But a synth is also a good beginning option and there are so many good ones out there. If you get a boar, you just have to make sure you shampoo it when it arrives and soak it in water for a few minutes before you shave (they absorb water and soften up in the process - if started dry I find them too stiff and absorb lather instead).
Hope this helps!