Very new to dwc. Fresh start questions

Getting ready to start over after a not so good first attempt. I have questions before I go at it again. Any and all info is really appeciated. I'm doing dwc 20 gal, Rockwood cubes, hydroton, and cyco grow and cyco bloom. Growing auto dems.First question- best way to go from seed to pot. Sprout in rockwool? How deep in the cube? When to put it in the pot. Water and hydroton depth in the pot? Second question- Nutes-- After the sprout is in the pot, how long do you run straight water before adding nutes? And then what is a good ppm increase through the process. Third question- water preference??? And if your answer is RO or distilled, how to deal with calmag def. Effectively. Please help

1. I use rockwool to start seeds, no complaints. Don't have to worry about depth of seed - just drop seed in hole and cover. I transplant to net pot when there are a good amount of roots trying to escape the bottom of the cube or when I have to dampen cube more than 2x /day. I put about 1" of clay pellets in net pot first, then add cube (after removing paper enclosure), and surround/cover with clay. Nowadays I prefer to submerge the bottom inch of the net pot. Extra gal /bucket doesn't hurt and I had faster initial growth. Anecdotal claims only I realize, but I won't go back to leaving a gap of air.

2. I use 50/50 city water/ro until new plant growth is looking deficient in something. Usually a couple of weeks after sprouting - about a week after transplant. PPM is an arbitrary measurement, just keep it low and watch your plants. If they look yellow, add more.

3. ^ 50/50. I had issues running 100% tap water. Primarily in pH stabilization and stunted growth at nutrient changes - let water sit for 24hrs blah blah still had issues. Went to 1/2 RO and it was like night and day. I have a bottle of cal-mag that, last run I added to my nutrient mix as needed. Ended up being around 1/4 strength of label (label says 3-5ml /gal, I added about 1ml /gal) for mature plants.

Thanks bro, that info on the water, ppm, and calmag is gonna help me out a lot. The rockwool and hydroton question is where I'm getting different answers. I posted the same question on another site and somebody on their put their rockwool cube all the way at the top of the pot with the roots feeding down through the dry hydroton with the water level an inch into the pot to start then reducing water level to 1 inch below the pot when roots come through the bottom. I'm doing autos in a 6" pot. In saying that if my cube is 1 inch from the bottom of the pot and these autos stay so short in veg that essentially the first three weeks of my veg will be inside the pot. The one that I have going now that I've had some small issues with I had one inch from the bottom sitting on an inch of hydrogen and solution in the pot and I think it gave me root issues cause the rockwool cube was saturated all the time. I also made the mistake of following the manufacturer's recommendations on the nutrient solution and was way way too hot for my seedling and didn't realize it till I got my ppm meter which I'm sure cause some damage as well. Is it really okay to have the cube sitting right on the solution and being saturated all the time? Can't it cause root rot? Here's some pics of her now, you can see how close the veg is to the hydrogen because I put my rockwool cube too deep in the pot. Getting ready to start up two more wanna make sure I get it completely right this time. Definitely going to have my solution low low to start. Lemme know what ya think. Thanks for the help

You'll always hear conflicting info on that. The idea is to bury the roots so that light doesn't hit them. If you need the space, put her over more hydroton. Pythium can happen no matter what, I've not had issues bc of rockwool.

When can you start top feeding through drip stakes?

I do not do any top feeding - it's not necessary at all.

Ditto, never really had a need to top feed