if you want transparency you want to do
SetEntityRenderMode(client, RENDER_TRANSCOLOR);
SetEntityRenderColor(client, 255, 255, 255, x)
where x is how transparent you want the client to be
setting SetEntityRenderMode(i, RENDER_NONE) just make the player disappear and you don't need to touch sv_disable_immunity_alpha
for the wallhang you didn't say what needs to be fixed
but maybe
https://forums.alliedmods.net/showthread.php?t=265896 is what you are looking for?