Yes you can view brighter stars by day, as well as the planets Mercury (when it's at a greatest elongation is safest and brightest), Venus, Mars, Jupiter and Saturn. Not sure about Uranus, it mightn't be bright enough.
You can build radio telescopes in your back yard. As for the theory and technical stuff
The faintest star you can see with a 50mm objective in excellent conditions is between 9.5 and 10.3 (depending on which book I look in). This also depends on the quality of the lenses and your own eyesight. For a 100mm objective around mag 11 (again depending on the book) Doubling the objectives as in binocular may allow you to see more because of how the eyes work in stereo mode, but don't quote me on that.