Getting new fish

Don't put them in her tank. They will already be stressed as is. If you put them in three different tanks within a few hours that will be too much. It is probably better for the fish if you just wait a few days.
Secondly, but most importantly, I would decide what you want and find out all you can about those fish so you know how to care for them. Make sure you know how big they get, what size tank you need, what they eat, suitable tankmates, etc. Don't make the common mistake of rushing in and purchasing fish you know nothing about. Go to the store, make a list of what you like and find out all you can about those fish. People on these forums can answer questions you may have about specific species. It will save you time, money, frustration and the fish will be happier/healthier.

I agree. You should keep the trip home to a minimum. Plus adding them to her tank may introduce a disease that could wpie out all her fish. Yikes!

Spend today looking at some fish, then ask on this list or check out the fish descriptions all over the internet and figure out

1. How many of each fish?
2. Will the different fish work togther?
3. What do they eat?
4. Are they going to get too big for my tank?

That whole fish grow to the size of your tank thing is a myth. Fish will grow to the size of your tank, get stunted and die an early death.