#1 metal song: the kicks are triggered live or sequenced, right? Given it's compressed to MP3 and I'm on laptop speakers (sorry

), I think you have too much kick in the double-bass parts and a little too much click. I know click is desirable, but I'm hearing a little too much high range frequency and a little rich in the mix during the double-kick passage, less so in the other parts.
Guitars could use a little more definition in EQ. They wane SLIGHTLY in and out of tune with each other on the tracks, but I would guess overall that is how they should be...i.e.-not to clinical to give a more organic feel to the riffs. I would use a little EQ to try and pull them a little more forward in the mix, though. Dig the tracks and hardcore depth of the tune, and would love to hear it with vocals and tweaked in the mix just a little.
#2 rap song: I think your drum mix and sound is good for this. It seems to me that your overall master output is low on this track. Are you getting the same db as the first one? I know there is more going on in the other track, different genre, etc., but the master output seems low. Where you double your vocals in the rhymes, I would pull the doubled vocal down and concentrate on the primary in the mix. The doubled vocal sings with the primary vocal a lot and is not quite in tune with the primary. Good to have it where it is during the "answers" to the primary vocals though where one is rapping and one is adding something else to it, just not a good level when they are singing the same line.
Drums and vocals (once the above is done) sit well together. The background repetition synth melody could be pulled forward a little/doubled or embellished with some more background tracking to my ears.
I like the high frequency "swish" in the beginning accompanying the drums. It is reminiscent of a little "beat boxing" going on behind.
Nice tracks man.