yes, and yes. Furniture grade birch plywood at least 5/8" would be best, expensive, but worth it. Score it lightly in a latice pattern, and apply a light coat of glue (allow to fully dry) to improve adhesion.
Many will say particle board is Okay, but it only takes a small amount of moisture to get there and the board will SWELL and then pop your surface. It is well worth the extra expense to use proper and stable FURNITURE-GRADE birch veener plywood and do it right the first time.
Good luck with your project.
By the way, are you familiar with the trick of using the slats (clean) that you remove from PVC window blinds (no strings) to line up and place formica?
Contact cement both the surface and the back of the formica sheet, and allow to cure. Then place the slats crown side up (the side that will contact the formica) about every 2 inches with the ends hanging over. set the formica sheet glue side down on top of the crown side of the slats and align. holding in place, pull out the CENTER slat from between the counter surface and the formica, and push it in place. Work outwards from the center, one slat at a time in each direction, smoothing from the center. Then secure with roller designed for purpose, then router cut the edges flush.
Hope that made sense.
Oh, also do not seal the edge against your finished (and sealed) wood rail with clear silicone (rated FOOD SAFE) caulk, until the contact cement/formica surface has had a few days to a week or so to fully cure and remove all over-ooze completely before you do so.