You've asked enough questions, that the answers would "fill a book". For beach storm erosion, it depends on the beaches in your areas. Each beach faces a different direction, and "responds" to different swell directions, local winds/waves verses distant 'swells', etc... Heck, even 2 beaches, a mere mile or two apart, can have different factors governing what erodes the beach, d/t off-shore shallows, various incoming swell/wave directions verses corresponding compass-point-facing direction of the beach, etc....
For dry sand hunting, there's no "rules", since you are basically at the whims of wherever someone dropped/lost something. Ie.: no different than a sand-box or whatever. But for wet sand salt-water beach hunting, you're looking for where mother-nature "deposits" things, since the wet sand beach is always changing (assuming you're not on a calm harbor still-water-beach). Sand goes in and out with each tide and swell change.
Typically building up in the spring and summer, and typically moving out in the fall and winter storms. But that depends on swells and such, since some swells come from the south, for south america's "winter", which is our "summer" (equatorial storms that can send swells all the way up here). So you just have to check with the aces in your area, who have hit good pockets of erosion/groupings in the past, and see what weather/tide/swell patterns dictated the erosion they were in.
Good signs on the wet beach are: cuts (an abrupt drop-off type sandy mini-cliff on the wet, where it drops down), slopes (where it's un-naturally steep slope at some point on the wet), wet/low spots (where the wet sand comes in further and deeper than the surrounding sand), and "scallops". Scallops are the so-named because they look like inverted scallop formation, where the ocean has scoured out a sideways dip. But it has to be major, not minor summery shallow scallops.
When you get in a perfect erosion pocket, where mother nature has turned the entire beach into a "sluicebox", where you can't move for hours-on-end d/t the massive amounts of targets, you will never again return to dry sand hunting
