For the first group...
Gorguts. You probably know them, but this band was a big influence on Cryptopsy. Their last 2 albums are very heavy and technical... especially "Obscura". Try to find the song 'Earthly Love' if you can.
Necrophagist. They only have one album, but it more than fits with what you're looking for. It's called "Onset of Putrefaction". A lot of cool solos on this album as well.
Blastfame. This is Kataklysm's temporary drummer's band... They also only have one album so far... "Abstract Evolution". They know their instruments well.
Malignancy. Brutal, technical, yet catchy. Extremely brutal vocals. Check 'em out if you can.
Dim Mak. Basically Ripping Corpse with slight member changes. The closest comparision I can put to these guys is DiSalvo era Cryptopsy. DiSalvo sounds like a wanna be Scott Ruth. While you're at it, you can check out Ripping Corpse as well.
Demilich. Known for some of the lowest vocals in metal. Totally unintelligible. Mid to fast paced weird technical death metal. These guys could also fit in the experimental category.
Pig Destroyer. This one is different than the others I mentioned... but probably heavier than the bunch of 'em. Very technical as well.