Enchantment and other continuous effects priority
Yes, that is entirely correct. Whenever a continuous effect comes into existence, it gets a timestamp, which represents when it came into existence relative to other effects. And, all of those effects you described affect Layer 4, so as you surmised, the order in which they are applied depends on when they were created.

It's important to note that at the end of this sequence, there are 4 continuous effects modifying the land's subtype. Whenever you want to figure out what the land's subtype is, you apply all of the effects in order. This is important because it means that when one of the effects stops applying, you just remove it from the list. For example, if Gaea's Liege leaves the battlefield, the land will be an island.