Unclaimed Territory seems like the most useful out of the lands you suggested. I have already spent a ton of money on this deck, so
shock lands are not really something I feel like I need to get.
Evolving wilds and
Terramorphic expanse are also tap lands essentially. Play testing this, Mana hasn't really been an issue. Although I will say
Chromatic Lantern is something I have thought about. My group is not super competitive so things like
shock lands and
darksteel ingot, while very good aren't really high priority for me.
The draw is necessary, in any deck. I feel like some kind of draw engine helps in all forms of magic, but especially commander. I have never really had a problem with hand size.
Descent of Dragons is more to pop my mana ramp creatures in late game and bigger threats than 4/4 dragons, but I have been considering taking it out. However, Silumgar is also a board wipe. Ojutai can tap all the opponents blockers for me to swing in for lethal. There is also
consume the meek since most of the dragons are high cmc.
Earthquake is a great suggestion and
Cyclonic rift is a staple in commander, but I don't know that I would have blue reliably enough to be able to cast it.
The other cards you suggested are all great recommendations. Thank you for taking the time to make these suggestion. I appreciate it very much. Cheers!