I'm just glad to see you're taking our advice and trying to do what's best for your fish

Having a look at your stock list, I must say you're fully stocked already and really recommend not getting any other fish at all. The guppies and platies, do you know the sex of them? If it's a m/f combination you will end up having a lot of fry very quickly, and this will overpopulate your tank in no time. It's also recommended to have 2 females to every male when it comes to livebearers (Platies, guppies, mollies and endlers to name a few) because the male will not stop harrassing the female. When there's only 1 female around, this will stress her so much it often leads to the death of the female.
I'm also afraid the flying fox will get too big for your tank, I'd personally say they'd need at least 20 Gallons. Are you planning on upgrading your tank to a bigger tank or getting a bigger tank at all within the next 4 months? If so, I'd say you're ok with the stocking you've got going on right now, but if you're planning on making this your only tank you'd be best off finding a different home for your livebearers and flying fox.
About feeding of the fish, especially when cycling, I recommend you only feed them once every 2 days rather than every day. And if possible, try and get some frozen bloodworms for them instead of just flakes, this is higher in protein and should keep them stronger and healthier when going through a difficult time when cycling the tank.
--Edit--
If you can't find any water conditioner in your fish shop at all, you could order it of the internet and get it shipped to you as well
--Edit again--
Just thinking ... when you bought the harlequin, was it already missing it's eye? Or did it lose it in your tank?