I'll try and adress your list (the stuff I know about anyways):
1) Spices: widely available here (even taco and fajita mixes and stuff) even some new ones we discovered here that were not available back home.
2) Splenda: No idea i'm affraid, we don't use the stuff.
3)Crystal light: We could not find it here, so my wife brought it from Canada on her last visit....bring it with you if you are addicted to it as she is lol.
4) Vanilla: I don't know if you mean the bean or the extract. Vanilla extract IS available here in supermarkets.
4) Marshmallows: definetly available here, I picked some up just last week from the Carrefour.

5) The stuff WE found missing are specific brands (ex: Cherios cereal...they have honey nut cherios but NOT just plain Cherios, we looked everywhere....Fruity TUMS...the heartburn medication....my wife always gets me from Canada....stuff like that).

Hope that helps, and good luck with your move.

Stay safe.

Perfection does not exist. The question therefore, is: what level of imperfection are we willing to settle for?