I'll preface my post by conceding I haven't kept a FOWLR for many years. So my advice will be partly based on recollection of what works well IMO, and bearing in mind that you're keeping hardy fish without corals. So here goes...
High flow within the DT keeps crap in suspension so that it can reach your skimmer. I'd have a powerful skimmer and I wouldn't use carbon dosing. Not because I don't think it works, but because its tempting as a new hobbyist to embrace concepts you may not fully understand. A lot can go wrong in carbon dosing if you're not paying attention IMO, so its best to get a handle on maintaining good water quality first. Then you can work on fine tuning it - and dosing is just one way that can be achieved. :beer:
DSBs can crash. But IME when they do its usually because they haven't been set up properly to start with, used the wrong size grain & depth, not enough micro fauna to work in the bed, a precipitation event has occurred, etc.. You can also encourage a crash if you allow the bed to act as a nutrient sink. eg predator tank + heavy feeding + low flow + wrong grain size... you get the idea.
This suggestion sends a shiver down my spine, but...If you're going to keep predators, then maybe a true trickle filter wouldn't be a bad idea. The highly oxygenated bioballs provide an ideal home for nitrifying bacteria. But you'll need to get the balance right or you'll end up with plenty of nitrate. While macro is useful in exporting both phosphate and nitrate, I wouldn't keep it in an environment where decaying fronds etc accumulate. Again, excess nitrate is added to the system.
Finally, a lot of fish will tolerate high nutrient levels but some won't. Many nuisance algae and cyano blooms seem to thrive when nutrient levels are high and water parameters fluctuate. Guess what I'm getting at here is that a lot of thought now, will prevent a lot of headaches for you later.
So all the best with your new tank!