Hi Nahara and WELCOME TO FISHLORE!
Glad to know that you're starting a 120g planted tank with a Guppy family. Sounds like fun! As Nick said, best to get 2 males and 4-6 females. Don't have too many, then you'll have loads of work to do. Start with 2 males first. If you're doing fine with them, then you can move on to more

"Everything has to start small first before you can reach for the top"
You could find great deals of second hand tank on Cragslist. Many members here check out that site and find such great deals.
Angels basically eat any fish that fits in their mouth, so yeah. Cories would do nice

You could get a school of them, 6 or more.
Best of luck and hope to see pictures up when you set up the tank.
