[Nectarines]

Hey all, I live in Toronto, Ontario, just recently joined ̶a̶n̶d̶ ̶a̶m̶ ̶i̶n̶ ̶t̶h̶e̶ ̶p̶r̶o̶c̶e̶s̶s̶ ̶o̶f̶ ̶g̶e̶t̶t̶i̶n̶g̶ ̶a̶g̶e̶ ̶v̶e̶r̶i̶f̶i̶e̶d̶.
I looked around the forums and so far found quite a few answers to questions that I had, but I'm currently looking to buy a good starter gun and after talking to my local airsoft store decided on the G&G CM16 Raider/Raider-L.

I'm planning on taking it into a nearby indoor CQB arena for some speedsofting. Yes, I keep coming across posts saying it's bad, but I'm also planning on joining an 18hr milsim in Picton, I believe it's called NightFall; not too sure, friend just briefly mentioned it, I'll edit in more info when he responds.

So, onto the questions:
Is the CM16 Raider(L) a good choice for a beginner gun for both CQB and Milsim ops? -Note: The arena does do rentals and they are Raiders, I tried them and they seem a bit unwieldy in CQB, might just by my small build.
EDIT: Should I invest in a collapsible/foldable stock if I decide to get the Raider?
Should I invest in something a bit more, but comes with a full metal body or just purchase a full metal body upgrade kit when the stock body starts to warp?
Also can someone give a list of things to consider when preping for milsim, such as how many mags should I have on hand.

If these questions are already answered, can you please link the posts below? Thanks~