Most of these things can be answered just by checking the common internet sources - try to google, try wikipedia.
What are half cell equations and overall equations? Are they
Cu2+ + 2e-=Cu? Or is it the same thing as a cell diagram?
These are three separate things. Redox process consist of reduction (one half cell) and oxidation (another half cell). Each process can be written as an equation where electrons are produced or consumed - these are half cell reactions. When you combine them, you will get overall reaction (and electrons will cancel out). Cell notation is a way of describing the system not in terms of reactions, but in terms of their construction.
Also what are reference electrodes? Are they like the standard hydrogen electrodes? Are there other reference electrodes commonly used?
https://en.wikipedia.org/wiki/Reference_electrodeAlso what is standard reduction potentials. Is it just the table with the voltage of different elements relative to the hydrogen electrode? Or is it more than that?
Not of elements, but of half cells. Permanganate is a strong oxidizer, one of the reduction reactions it undergos is
MnO
4- + e
- MnO
42-This reaction has a standard reduction potential of 0.564 V. No elements here, just an oxyacid anion.