It's amazing

Yes

Play vanilla once first at least is what I'd recommend. Space Age you don't get stuff like cliff explosives until you go to a certain planet. That's not critical, but it does make things harder. If you finish vanilla and want more, Space Age is well worth it.

Vanilla will prepare you for the challenges of Space Age. I don't think new players will be prepared for it. It's not particularly challenging, but it does throw some curve balls that experience helps with. It'll also make vanilla feel so much more shallow, so your experience with that will be lessened.