Hit the down arrow next to Recharge, then unmark the other options. Alternatively, after opening the drop down menu, hit "Clear," then recheck Short Rest.
This chart doesn't measure the comparative strength, only recharge time. I don't consider myself well-versed enough in the rules to be an accurate judge of that (also, it would require a lot more work and effort than I have the time--or will--to put in). You're welcome to discuss it here, though.
Not necessarily. This list doesn't include things like raw spellcasting, because it's a different system. It also doesn't include things that are at-will or one-time-use, because that would be the majority of abilities. This list is primarily intended for use by DMs who want to compare which PCs of theirs would benefit from a short versus long rest, and plan their encounters accordingly. It's assumed that the DMs would either know their PCs abilities well enough to judge their strengths or have the PHB and use the provided page references to educate themselves.