Easy

-When should i plant these outside? (How should i do this?)
when they have established a rigid stem and a few nodes worth of leaves.

-Should i split up the 2 plants in the red cup?
never should have planted in the same container to begin with, unless for some retarded reason you were going to grow them in the same container one inch from eachother for their life. Split asap before roots become entangled to the point where you kill them splitting them.

-Should i add miracle grow or some type of soil or nutrients to these plants grow?
You should use soil intended for your application, that being said, do a little reading, everyone is going to come up with a soil system/nute program that works for them. Kinda gotta earn some stripes here

-What should i do to help the weak plant get stronger?
try giving it more light. Plenty of threads on here about how to have complete harvests from CFL bulbs you can buy at home depot.

-Any other tips would be well appreciated
look around here at others grow logs. and if you have a question, try using the search feature on the forums and look for whatever keyword you need.

Don't seem needy, as in, I need help setting shit up. You probably need a lot more help than anyone here can give you from the sounds of it, that's why you need to get dirt under your nails and share your fuck ups and what you learned from them with the rest of the world. I'm stoned off my beautiful homegrown, so I'll quit rambling.

Peace love and dope bitches, i'm out.