The section on "Jumping" lumps both forms together
Your Strength determines how far you can jump. [...]
It then describes both long jump and high jump, so we can conclude that "how far you can jump" refers to both types of jumping. This also matches a standard English reading.
When a feature benefits a certain type of jumping it specifies as such
Yes, it affects both
The language used in the PHB and other books is very particular. Writing your "jump distance is doubled" and not "your long jump distance is doubled" would be intentional. Thus, anything that affects your "jump distance" in general affects both high jumps and long jumps.
Using two hands is not the same as the two-handed property
You can use two hands to make an attack with any weapon, say a dagger, but gain no benefit from doing so. The versatile property of quarterstaffs give a benefit for doing so and the two-handed property means you have to use two hands with the given weapon.
The requirement for monk weapons that they ...
TL;DR; No, it cannot be aborted - you spend a ki point, allowing you to use Flurry of Blows as your bonus action.
The description of Flurry of Blows under the Ki feature states (emphasis mine):
Immediately after you take the Attack action on your turn, you can spend 1 ki point to make two unarmed strikes as a bonus action.
Basically, you spend the ki ...