For 100l set up I would not recommend 2 schools and guppies with other fish. That would be overstocking the tank. Not to mention that your guppies unless all male will breed and then you will have tons of fry to contend with. You could go with a school of 10 tetras, such as black neons, neons, or cardinals, or lemon tetras, with some cory cats for bottom feeders. You could add in some other fish like rasboras. I would have a small school of cories, some rasboras and a school of tetras if it were me. Lots of color with interesting behaviours.
What filtration will you have for your tank? Filtration will also play a huge part in how much stock to have. How often will you be doing water changes and how much? Are you planning on doing a fishless cycle first or is the tank cycled? On average with lower filtration and weekly pwc's you could average about 26" of adult sized fish that you have mentioned.