The answer to your 3 questions
"I just wanted to know, does construct have:
Game Centre Achievements.
In App Purchases.
Universal Binaries."
No, but CocoonJS wrapper has Game Center support
No, but CocoonJS wrapper has IOS and Android IAP, but the plugin is working with such features yet.
No, and unfortunatally unless some intrepid programmer reverse engineers the XML exports C2 will never have universal binairies.
"Those are some features GS has that I hope Scirra does.
Scirra has WAY more awesome features than GS, I wish I started with Scirra.
However making the change at this stage will be a little costly however as things go I do plan on doing it."
The only down side to C2 is that it's dependent on other technologies to advance to catch up. However I find that it's easy to make games with C2.
"Does scirra supply hard code so I can take advantage of getting programers to incorporate non Scirra features like multiplayer etc?"
You can program plugins for multiplayer and other features. Also the JS code is exposed so you can tinker with it as much as you want.
"Can Scirra make games like platform shooters with mechanics that allow you to shoot a bullet at a group of actors all together, overlap more than one and only destroy one? GS Can't do that and I would LOVE it if Scirra could."
Yes. Really depends on the condition of which you want to destroy.
You can set a condition event for overlapping. This will give you a pool of objects(actors). Then you can count through them, then random to destroy one of them.