3d camera problems

Hello there everyone, Im working on a 3d scene and having two problems ive tried to resolve by exploring the forum’s archive, but nothing came up!
first issue is with the particles in the scene that do not scale properly as the camera moves. for example if I have the fairies (from the library) and a tree, when the 3d cam is zooning out the fairies remain at the same size while the size of the tree decreases. when the camera peg is 2d it doesnt have that problem.
the second problem is with the blending module that not works the effect on my 3d scene. if the effect is overlay for example, the rendered effect doesnt show at all.
please let me know how to make it work guys. thanks