I am with @Cory about the bloodworms. I have 2 species of corys that are deemed delicate( duplicarearus and eques). Feeding bloodworms when you first get them helps a lot. Next thing, what else do you have with them? Faster fish can out compete for food and if you haven't had corys in the tank before you will need to add a little extra to ensure the corys get their share.
Attach a pic of the tank please. A lot of times there aren't enough plants in the aquarium to use up all the fertilizer, then algae will persist. It is a tricky balance.
Probably more then just a few days. "Greening up" depends on a few factors, lighting, available nutrients, and water chemistry. Try googling monte carlo care and research from there. Hope that helps.
Not sure on pygmies but 7 years ago I bought a wild colony of both duplicareus (12) and eques (12) from them. The last 7 years have lost 4 of the duplicareaus and 3 eques. I think that's a pretty good record. Since you will be there you can ask about their quarantine process and if there has been any issues with the pygmies.
Pleco won't help with BBA. Google excel for BBA control. This how i got rid of mine. It WILL take a lot of manual effort to clear the dead algae and you really want to increase the flow in your tank while doing the whole treatment. It isn't an easy task but it is doable! Good luck!
Use magic nano feed from aquarium co op. Bug bites don't work for me very well with any of my tropicals. Also crushed algae wafers. Using green beans I feel, can foul the water quicker