Hey hey again.
1- yes Cabomba is a is a excellent nutrient soaker, and its defiantly close to hornwort for ease of care. It can yellow and melt a bit easier though but its pretty hardy stuff. I basically let my stems grow quite long, and then prune them about a inch above a major Y in the stem and take the long prune that has white roots break of about a inch of leaves at the bottom. I do this to several stems and then take the cluster of stems and very lightly wrap a lead plant weight on the cluster of them and drop it to the bottom and let the roots find the substrate on their own. Has always worked very well for me, I found that trying to stick them in the substrate I risked breaking them and found the roots were not mature enough and failed on my part of the time.
2- Yes flourish does have iron it, along with many other macros, that is the only reason I am currently not using it as I am trying to see how effective bio ferts will be for macros for me, so I don't really want the extra nutrients it provides. That being said its a excellent fert, but I would tend to try using seachem trace along side it for your micros. But both in light amounts, unless you are doing substantial water changes weekly to reset the balance. Which you already do, so you are golden either way.
3- kinda falls back to number 2 with nutrients, dose light and watch for signs of plants in need of a certain nutrient and up that nutrient (this is harder to do with flourish as its basically a multi, so in order to up one you have to up them all. When I was doing a sensible stock and full ferts, I did flourish in very low amounts and used seachems individual macros, iron, potassium, nitrogen and phosphorus each on their own as needed. I personally liked that route as I am not a big fan of large water changes, I think its just to much change to quickly. Method 2, dose harder then you will need to make sure your plants get what they need and do a large change weekly to reset the nutrient load, before algae gets a chance to feed. As far as algae eaters, I have my crew of SAE and shrimp and they are very good, but I also do my best to avoid outbreaks in the first place.
And as far as overstocking, that is a great thing that your not, I am in no way advocating overstocking as a means to a healthy planted tank. In fact quite the opposite I am basically just testing things out for a greater understanding of my aquariums needs as far as plant and fish health. And at the moment as my fish are still quite juvenile i am really not that far out of spec, but they defiantly will be as they mature. I am watching my fish plants and water parameters extremely close as I do care for my fish allot and in no way would want them to have a unhealthy life.
4- Yes overstocking does mean to much fish waste and very much can and a lot of times is a key source for algae growth and or outbreaks, very minimal spikes in
ammonia can trigger algae and is horrid for your fish and beneficial bacteria (they can only work so hard at there job before getting overloaded, but that is where I am hoping my plant base will aid them as plants are also a excellent feeder of ammonia. And as far as waterchanges I do very minimal changes weekly 5g out of my 50g, but I have yet to see any signs of toxins in my water at all. I also tend to not feed alot as well, I do two small feeds a day, one is always a quality flake/dry type feed the other is always a live or frozen feed, I tend to rotate latter around they get a few days of frozen bloodworms, a few days of frozen
brine shrimp then a couple days of live brine shrimp.
So basically I am trying to only leave enough in my tank after my plants filter them up for my filters to bring into their beneficial bacteria to feed them and keep them going. My plan is to watch my water, adjust filters as needed, (as right now I sit with two filters that could each run this tank on there own running at about 70% flowrate, and a fair sized plan base to absorb toxins as well) and watch carefully over my maturing fish colony and slowly start removing stock as needed if it comes to that, and there is a good chance it may.
Again, I don't want anyone to get the idea I am treating this as a way to grow plants, as Isabella is right, overstocking is one of many triggers, and there are many. I am solely running a test for a better understanding of my tank fish and plants, as I want to find a balance between ferts and stocking in my aquarium.