As far as I can tell, the original had many things scripted and the AI most certainly bypassed many game mechanics. For example, there were reports of alien fleets gaining full strength out of blue. In the original, radar didn't affect the AI and could attack any fleet or planet, even out of sight ones. In Open-IG, the aim is to make the AI adhere to the same rules as the player.
I think the extra Ychom minelayer make it more interresting to capture a planet. There are several strategies available: use rocket sleds to destroy buildings and cut through the footprint as the minelayers only place mines on roads. Attack power plants from distance to cut the power to the barracks. Attack in tandem with a second fleet and more tanks.
If you are into some modding, you can find the tech.xml in one of the zips, locate the YchomMineLayer entry and add a <property name='one-per-fleet' value='true'/> under it to limit the number of items.
Controlling time in battles was a no-brainer. Since the AI would essentially micro-manage its own units, the player should be able to do it as well without any time pressure.