You know im probably what you call a pleeb in this type of work and even i know amps are not good at all esp. after seeing some guy give advice to another by adding a amp and directly after warning that he'll cook most trees within 50m (now if it can cook a tree imagine what it'll do to everything else). Omni's not too sure why they so unpopular but just one of those things you'll learn with experience.
and the cable, just another obvious point, basic school science... cable will create "friction" so why make it long when you can have it short... it is only a box and if it isnt aestetically pleasing then paint it