Where should a beginner start..?

Hi Beth. Welcome to our forum.

The short answer is, you are overthinking it 😉

Praecox Pagai are a very popular fish. They are awesome, especially kept in big groups.

In a 29 or 40 g, I'd go with about a dozen. Male/female ratio doesn't matter so much as getting healthy fish and keeping them in bigger groups.

Plants are great, but the fish do need room to swim. Lol. Rainbowfish are pretty hardy. If your plants are growing, Rainbowfish will probably be just fine.

Have you checked aquabid.com for Rainbowfish? Some of the best bow breeders have fish listed right now.(I didn't notice if any praecox were listed)

Since forums almost died,, we have a Facebook group, Rainbowfish Live. Many from the forums are there. We just surpassed 6200 members. Yay! And some actually know what they're talking about. Lol. Facebook is a necessary evil--But, it's worth checking out. Lots of pics and videos posted by our members. (For ideas on how many plants, etc)

Since you liked aquarium co-op's live video with Gary, did you also see their tours of his fishroom? If not, look them up. You'll find your answers. Dustin's Fishtanks has a few videos with Gary too.

We made a different website...where people can post what they have for sale. rainbowfishuniverse.com

There's also "Home of the Rainbowfish". Run by ANGFA.(Australia New Guinea Native Fishes Association) They also put out scientific publications.

My well water is even higher pH than that and I have not had issues with my Rainbowfish. Consistency is most important. Decide what you're willing to do every week or 2 for the next 5 years or so? Rainbowfish can live longer, but praecox don't usually live much past 5 years. But by then you'll probably have a fishroom full of rainbowfish. Lol.

Hope that helps
~Lori