RE: How much CA?
Luckily this isn't a Balsa airplane. That means instead of soaking a bunch of glue into balsa you will instead be using tiny drops that will spread out over large areas of plastic. Think Glass microscope slide and shield and just how far a tiny drop of water goes with that combo. I've done some recent building on 3 SPADS and all I had to glue with was the last 1/8 inch of glue in my CA bottle. Still have some left!
Now granted, the Spadet has some wood parts in it, but I would think that a 1 oz bottle would probably get you through the plane in flying colors if you do glue correctly. If you instead squirt lines of glue like they were 'HardasNails' contact cement, you'll be out of glue fast and your joints won't be very strong.
In the end, your mileage will be different from everyone elses. But here is the best bet. As we use so little glue compared to a Balsa plane AND the best joints come from fresh CA. Buy your glue in small bottles 1 at a time. It goes a long way and that way you won't have a 2 ounce bottle of glue going stale or getting knocked over while you wait on money to start your next SPAD build.
In a couple weeks, if you really use a large amount of glue, you can go buy another bottle.