Following Step appears, to me, to pretty clearly indicate that it modifies Step Up. It's not an either/or proposition - to use Following Step, you must be using Step Up. So, reading them together, Following Step allows you to take a ten foot "5-foot step" which doesn't provoke AoOs and also doesn't subtract from your next turn's options (it still costs your immediate action). While you could theoretically use Step Up without the benefits of Following Step, since feats are optional unless otherwise stated, there's no reason to: Following Step kicks in as part of using Step Up, which means it applies to the 5-foot step granted by that feat.
The following rules citations were stolen from Hey I Can Chan's answer, bold emphasis mine:
The feat Step Up has as its benefit:
Whenever an adjacent foe attempts to take a 5-foot step away from you, you may also make a 5-foot step as an immediate action so long as you end up adjacent to the foe that triggered this ability. If you take this step, you cannot take a 5-foot step during your next turn. If you take an action to move during your next turn, subtract 5 feet from your total movement.
The feat Following Step has as its benefit:
When using the Step Up feat to follow an adjacent foe, you may move up to 10 feet. You may still take a 5-foot step during your next turn, and any movement you make using this feat does not subtract any distance from your movement during your next turn.
Closing note: I know, a 10-foot "5-foot step" doesn't exactly make sense. A 5-foot step is a defined game term, though, which means it works well as a shortcut - it's a quick way to say you can move 5 ft without provoking AoOs. Weirdness like that happens when one rule modifies another - such as allowing a 5-foot step to reach 10 ft.
You have two questions there:
- Can the Boogle make the rift open next to a bag of holding?
- Would the rift tear apart the bag of holding sucking everything into the Astral?
Can the Boogle make the rift open next to a bag of holding?
Yes. But the boogle needs a frame to anchor the opening, no bigger than 10 foot apart.
To create such a rift in space, a boggle must be adjacent to a space defined by a frame, such as an open window or a doorway, a gap between the bars of a cage, or the opening between the feet of a bed and the floor.
If it desires to move through completely, the frame must be one that would allow the boogle to move through. The mouth of a bag of holding cannot be considered a frame.
The rift exit can open right next to the mouth of the bag. No problem in that. But it would still be immovable. The boogle could step into the bag (but could not get out alone) or move the bag through the rift.
Would the rift tear apart the bag of holding sucking everything into the Astral?
No. The rift is just a dimensional opening, not unlike a dimension door spell. it is not an extradimensional space. No extra space is created by the rift.
Best Answer
Yes
The rules do not define "teleport" so its normal English definition applies.
If the dryad is within an opponents reach then by stepping into the tree they trigger an opportunity attack if they leave that reach because this is normal movement; a "step". The transfer from tree to tree is teleportation and would not trigger an opportunity attack.
Of course, normal opportunity attack criteria apply, if the dryad can't be seen or takes the Disengage action then no opportunity attack.