Nothing wrong with either. Aluminum shafts as a general rule will be heavier than carbons. Carbons are less susepetable to damage from miss-use, carbons are generally more quiet. Aluninums are much more straight than carbons. If an arrow were to "blow up" it's more likely going to be a carbon and unlikely an aluminum. I can't think of more differences between the two. I use them both.
As far as broadheads go some where between 100 to 150 grains is good. The lighter will give flatter trajectories and the heavier are better for momentum or plowing through your intended target or quarry. Look for a short broadhead. Three is better than four blades but not by much. There are tons of great broadheads but if using one with replaceable blades find the ones that self-support the blades. The issue with Thunderheads is that they are not self supported and they are too long for really fast bows. Here is a starters list of good commonly used broadheads in crossbows. Slicktricks, G5 Montecs and Strikers, Muzzys, Steelheads, Rage, Spitfires etc. Hopefully others will mention some broadhead names. But keep in mind that this is the internet and you have to sift out the rocks. Depending on what insert you use you will want to use the weight of the broadhead to get a desireable FOC(do a search on this subject) which is basicly the balancing of the shaft to make the front heavier.