Teijo Lukkarinen

You can also downgrade a level II effect or deactivate regeneration by breaking the lowest layer and reactivate them by restoring the layer.

This is different from BUDs. BUDs activate with any block update, this one needs a redstone update. The dispenser turret uses this same bug to rapid fire dispenser 10 times a second by redstone updating the powered dispenser with a 1-tick clock.

You can only clear exactly one block gap when fully sprinting. If you go at the gap at a slight angle you won't clear it. Also trying to go over with only a little start of 1-2 blocks you also won't make it because your sprint isn't fully engaged. Can seem buggy but it's just very strict about the circumstances. Maybe it could be changed to allow a bit more leeway so you wouldn't have to go straight in a cardinal direction but couldn't still clear wider gaps.

This is different, happened before the 1.4.3 change as you can see my game version is 1.4.2. Even in 1.3. It is a duplicate of MC-195 actually, not MC-1612. But yes, sorry for not searching properly but you failed to discertain it from the other bug.

That is an intended feature.