Does equipping an equipment go on the stack?
Equip is a regular activated ability. It goes on the stack and can be responded to. If it didn't resolve yet, the targeted creature is not yet equipped and does not benefit from the equipment in any way.

702.6a Equip is an activated ability of Equipment cards. “Equip [cost]” means “[Cost]: Attach this permanent to target creature you control. Activate this ability only any time you could cast a sorcery.”
602.2. To activate an ability is to put it onto the stack and pay its costs, so that it will eventually resolve and have its effect. [..]