Fish feeding questions

[rocketlily]

At the moment I have 2 very small fish. One Pyjama Cardinal in the main tank and one Scopas Tang in QT. Both fish are very small and do not eat alot at one time. I would like to feed them twice (maybe 3 times) a day.

I would like to feed them a mixture of chopped Mysis, a little bit of Brine, a drop or 2 of garlic and a drop or 2 of Selcon. I will be also be putting in a little bit of Nori on a clip for the Tang. With time restrictions, like having to go to work in the morning, there isn't enough time to make up a mixture. Plus with both fish being so small most of the mixture goes down the drain.

The questions I have are:

1) If I make up a small batch in saltwater, how long can I keep it in the fridge and safely feed it to them?
2) What else can I add to the mixture to make it healthier for them?