Lol, I think most people started to read your post but then they decided to quit while they were still ahead. They didn't want to get 2 hours into reading to answer a couple questions. LOL, JK. Anyways on to Q & A.
1/dimmer) I would get the dimmer if I were you, it will allow you to fully maximize the light. Without it, it's either on or off. If you ever were going on a vacation or what not you could dim it for slower growth and insurance for algae growth.
2/green leaf ferts) yup, I think of all dry ferts as the same it's just how the quantity and container correlate with the price. I have some from both GLA and nilocG. NilocG is going to be cheaper on average (I believe).
3/substrate) start with 2 bags if that's not enough you can put lava rock rubble under neath to boosted it up a little.
4/plants) I really love dwarf hairgrass belem, and Monte Carlo is much like HC just not at all as demanding.
AR mini would work fine but I am very partial to Anubis nana petite for a foreground, especially a nice cluster of them.
Here's a few stem plants that I like and others like on this forum. I didn't ad any that are super demanding and I think almost all of them are "medium" in the ease to grow rating. A couple of them are not quite background plants but I like them so your gonna just have to look at them (LoL).
5/Fish) I like the chili's but if you bump that rummy school up, they will actually school. Rummys school very nicely in bigger schools. I am going to be putting right around 50 in 65 gallon of mine in the next couple of months. Amanos are my saving grace for when it come to algae, and they will be yours too. No bottom dwellers are "needed". But Cory's are really cute and a group of 4 or 5 would look nice.
6/scape) TBH I have no clue what the vision is until you post a picture, but once I see a picture I will be able to fully help you with that too. Hope it helps, make sure to post pics.
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