I'll leave the tough stuff to the real smart guys like TFOX and Swampcollie, but I think I can get you started..
The reason the guy said be careful of arrow weight is if you go too light you can snap the limbs due to excessive energy that is exerted onto your limbs, as well as everything else.. So, first you need to find out what the draw weight is on your bow, then, AT TE VERY LEAST, maintain 5 grains of arrow weight per pound.. So say I shoot a 70# draw weight, I would want an arrow that weighs atleast 350 grains (including bh or field point)..
Now, not only is arrow weight important, but to shoot properly and have the arrows fly true, you will need to see what spine arrow you would need.. This can be figured out if you give a draw length, draw weight, arrow length as well as what weight tip you put on your bow.. (this is where TFOX and SC can help)
Additionally, If you go to any bow shop that knows anything at all they should be able to set you up properly.. proper spine-proper weight--all that good stuff...
Hope that holds you over until TFOX or SC can jump in..