As far as the hiding....you don't have any aggressive fish in the tank and you just put them in there and have a nice shoal, so I'm pretty sure they just need to settle in. I just bought 12 last night and they are just now this night coming out and exploring/shoaling around more.
My problem is some of mine aren't eating the bits of flake that make it down to them from the top. Are yours eating? It has been a really long time since I kept them and remember keeping some small pellets that sank that I fed them but I don't remember whether they liked this or the regular flakes more. Maybe mine just need to settle in too.
BTW - you might be a "newbie" but you have one of the best looking tank setups I have EVER seen. I gave you a 9.