According to my testing, if the opponent somehow disappears from the hitbox on frame 9 (which happens in many more situations than most would think, sadly, given that this seems to happen on a regular basis to me), the sticky just falls to the floor. For the stick to happen, it's absolutely necessary that the opponent is in the hitbox for frame 7, and presumably frame 8 as well (though I can't think of any convenient scenario in which the opponent's in the hitbox for frame 7 and 9 but not frame 8).
As for wavebounce stickies, I personally haven't had time to invest into incorporating it into my gameplay yet, but if anyone needs a more explicit list of inputs, using standard numpad notation (6 forwards, 4 backwards, 2 down, 8 up, etc), I believe the input would be 64(2B)364.
EDIT: Scratch that; it turns out that it's more of a 6(1B)64 input, and seems like it's a bit more trouble than it's worth: wavebounce only has a few frames for input (unsure of how many), Snake has the worst aerial mobility in the game, so you'd need to get a running start to get the wavebounce to go anywhere, which proceeds to make the effective hitbox of the C4 Jigglypuff-rest tier. It may have a niche use as a mixup for avoiding retaliation (In the sense of "is he going to go behind me or wavebounce), but that's a bit next-level and overall it seems that if you're going to stick, it'd be better to just go straight through the opponent afterwards. It opens up an opportunity for a back air if the opponent's still in hitstun after the stick (or about to land)