Welcome to the forum Jay
Is spruce and eculpitus easy to cut ?
Both saw OK. Knotty spruce can cause issue with a bandsaw due to the blade wandering when it hits a hard knot. Eucalyptus tends to be pretty hard, and can have a lot of tension that you have to deal with. Both both saw OK as long as your mill is all tuned up properly.
Does it last outside untreated ?
Neither are considered particularly durable.
The NZ Spruce will be pretty fast grown. Certainly usable, but not the prized aircraft or musical instrument grade stuff.
There are different species of Euc, but the common ones here in NZ aren't that durable. Certainly not ground contact durable anyway. The hardness of the Euc makes it good for flooring / counter tops etc. Assuming you can get it to dry straight
Macrocarpa will probably be your favorite to work with though. Saws and dries easy, smells great, durable outside, or pretty enough for furniture.