Yes, there is a difference between reasonable suspicion and probable cause. Reasonable suspicion is a lower standard than probable cause. The courts deemed a pat down, or “Terry Frisk” (stemming from the name of the court case), less intrusive than a full on search. For an officer to pat somebody down, they have to have reasonable suspicion to believe the person is currently armed and dangerous. Since reasonable suspicion is a lower standard than probable cause, this doesn’t take “evidence” per se. There are numerous factors that can give an officer reason to pat someone down, but I do not think NYPD’s policy meets the standard.
A Terry Frisk is not supposed to involve reaching into pockets. It is a pat down of the person’s garments/body to ensure there is no weapon on them. For an officer to pull something out of a pocket, they have to be able to articulate that it felt like it could be a weapon. This is where it gets complicated as far as drugs/paraphernalia go. A glass pipe in someone’s pocket is hard, and the general size of a pocket knife. A baggy of weed does not feel like a weapon. However, courts have upheld officers pulling drugs out of pockets if the officer immediately recognizes the feel of (this is the only specific example I remember from training) a crack rock the way it slides between a plastic bag.
Probable cause is a higher standard, and what is needed for an arrest (different than a detention) or a search/arrest warrant. This requires actual evidence rather than reasonable suspicion.
I hope this helps. This is all based on the training/schooling I have been through at both the state and federal level of law enforcement.
As for the second question, I think that is best left up to Mr. Woods and his staff!