mobile design for sprite heavy game?

I need to advice about the design of a game that contains alot of sprites (about 3000)

in 1 scene.

first, is it even possible or should I divide the sprites for mulitple scenes?

the reason I want all the sprites (which are static btw) in 1 scene is becuase I want to do a smooth movement of the camera between levels.

if it is possible, I'd like to know a couple of thing related to the design:

1. should I instasiate them all before the game begins, during the level, or just put them myself in the editor manually (the mainCamera only sees 30 sprites when the scene loads).

2. should I use LoadLevelASync from the main menu, if so, when? when the main menu loads? when the player click start?

any advice regards the designing would be much appreciated!