eventually, you'll end up with a selection, and then, after that, you'll find what works for you.
yes you can do hats with magic loop (and you can do hats with half magic loop on a 32 inch needle!)
its impossible to tell you what you need, what is best, because--there are so many choices, and everyone suits someone!
i have 50+ year old needles (circulars needles with metal cables, not nylon cords)
and i have needles less than a year old!
the interchangeable sets are worth while.. they give you lots of choices, and can often be resold (or swapped) for something of if not equal, 90% value.
so look for a 50% off coupon, and buy a boye interchangeable set..
if you don't like it, sell it and try a Denise set...
don't like that? try the Knit Picks set...
one is bound to meet your needs (and budget!)
but, as the years go by, you'll notice you have more and more needles--no matter what!
i, um, have, um, over 20 size 8 needles
straights, (both long and short/metal, bamboo, plastic) DPN's, (metal, bamboo, plastic)
and the same goes for some other (but not every) sizes of needles! i never set out to have 20 needles the same size.. but it happened!)