I would go with the chunky yarn first because it won't take as long to knit as the garment in DK yarn. My first garment was a zip-up cardi in chunky yarn, and it went very fast; thus, minimizing the possibility of working on a "never-ending project" as my first one.
I would recommend inserting life lines when you get to the trickier sections of your sweaters. That way if you mess up or don't like your design ideas, you can rip back and try again (provided your yarn isn't all snarly from the ripping and retrying).
And as for this being too adventurous--says who? My recommendation is to try it. You can always come here and ask for help if you get stuck, and besides, you never know what you can accomplish until you try. If you get frustrated to the point of ripping your hair and everything else out, then reboot and start with a simpler written pattern.
We'd love to see your finished objects, so please hang around and post some pictures when you're done.