tomato growing project, please help :)?

If your going to grow them outside at all I would wait till there 8" then dig a 1 foot whole (wide) and 6" whole deep and add the miracle grow soil with regular soil (you can add very finely crushed egg shells and or a little horse manure and or coffee grinds no bull blood)

Then mix it all then carefully plant the tamato plant but make sure the lowest leaves are about a inch from the soil once its around the plant then water everyday for 2-3 days not to much. (this is for each seedling)

If inside or in a pot you will need a 1-3 gallon pot of just miracle grow and replant the seedlings water everyday for 2-3 days

Don't fertilize till the roots get used to there new soil and or pot wait 2 weeks or so then you can use fertilizer

Definitely yes. You can transfer them in a bigger pot. Anyway, there is a process called - transplanting- in a plant's life cycle. It is planting sprouted seedlings from nursery bed, in this case your 4 inch pot- to the final planting ground where the plants will grow, flower and fruit-which you are about to do transplanting your seedling to an 8 inch pot.

Just be careful not to damage the roots. You can do it by carefully shaking your 4 inch pot upside down to loosen the soil where your seedlings are growing. It should come out like a ball, the soil intact. Then carefully put them in your 8 inch pot and cover your miracle gro potting mix. Do not expose them to sunlight right away. Keep them covered from direct sunlight at least for three days.

You do not need to use horse manure. Or egg shells, coffee grinds and bull blood. It takes time for these to turn into organic fertilizer. Just use the fertilizers you bought and be very careful in its application. Use directions from its package label.