I setup my first planted tank (40g) about 5 weeks ago, and I'm having some issues.

I've gotten most of my plants from fabulous people here on TPT, so they've come from a lot of different tanks. I'm not sure if that matters, here.

Issue 1: My tank is still not cycled after 5 weeks of using the fish food method; I've even used SeaChem's Stability, which was recommended by a lot of people here (and on Reddit, and in my LFS) to speed up the process. I tested yesterday (API liquid tests) and ammonia was about 2ppm, nitrites and nitrates were at 0ppm. I'm starting to think the things I used to treat the water when I set up the tank are to blame; I noticed after the fact that one of them "removes nitrites and nitrates" (NovAqua+). Could that be preventing the tank from cycling properly?

Issue 2: I've got rust-like algae on the leaves of some of my plants, which from browsing the algae forum I've learned is fairly common for a new tank. Should I do something to get rid of it? If so, how do I treat it? The tank has a single fish (neon tetra), who has lived through all this cycling mess, so I don't want to kill him now by trying to treat algae.

Honestly, I have no idea how he's still alive. I feel terrible that of the 5 fish I added when I started using Stability, 4 of them died. The one left is obviously immortal, so I named him Zeus.

Of all the other tanks I've cycled/kept, I've never had it take this long just to START the process. I mean, I don't even have any nitrites yet. Granted, this is the largest tank I've ever had, but... man. :/

Suggestions/comments?