Hi Indir,
When you state your water stats you're not saying how many hours it had been when the stats were taken from the time when the ammonia add was made. This is an essential bit of data for people judging the results. We would expect you're reporting stats that were 12 or 24 hours later, but just to be sure its good for us to ask. The stats are obviously looking better.
Your tank changes look good and your stocking plans are very reasonable. Danios, D.Gouramis and Bristles are all excellent starters (D.Gs are subject to a particular D.G. disease, but I feel this is one of those things where either yours have got it or they don't, so if you just prepare yourself to understand that, its worth the risk I feel as they are nice fish.) The neons are better left as an add 6 months after cycling is over, but are of course a great fish.
The beta is a whole different story. It (like the gouramis, actually, but more so) is subject to an individual personality on an individual fish basis. There are definite considerations depending on male/female and depending on other species in the tank (the gouramis may rule it out, right there, but I'm not an expert.) I'd recommend you absolutely not add a beta (SFF) until discussing it with OM47 and/or beta forum folks.. doing some study on it etc, like you've done with other new aspects of the hobby.. you've been pretty good at this! (also, I see MW has already commented, so that is another source of knowledge about betta behaviours.)
One more small thing about the danios. The leopards and zebras will probably just shoal together (to the extent they shoal, which is less than tetras or just different in nature) and in my opinion the more plain silver look of the leopards will just dilute the stronger effect of the zebras. But there's nothing wrong with mixing whatsoever and its an individual choice and may be more interesting up close when you look at them, so its your own choice.
~~waterdrop~~