Regarding the pricing of arrays, the easiest way to handle it is to remember that making an Alternate Effect, or making a power Dynamic, is considered to be spending points outside of the power (kind of like using a skill point to raise the attack bonus of a single power by 2 instead of buying Accurate), so it never affects the amount of points "spent" on the power.
There's a minor caveat regarding nested AEs, something unaddressed in the 2E or 3E books, but conditionally approved in the 2E ORQ forums by Steve Kenson (i.e. he thinks it makes sense, but it's up to individual GMs to decide whether any particular example makes sense). To give a mildly contrived example, let's say that you have someone who has a rifle and a grenade launcher. They make one an AE of the other to make it cheaper (since they'd never use both at once):
Rifle (Blast 6) [12 PP]
AE: Grenade Launcher (Blast 4, Burst Area) [1 PP for 12 PP of powers]
Now later on, they make their gun Accurate and add Improved Aim (e.g., adding a scope) as an Advantage, adding another 2 PP to that power. The grenades are OK as they are, except that they'd like to be able to launch other kinds of grenades. They could buy additional AEs for each grenade type, but why do that when they don't need 14 PP of powers in each grenade? So instead, they do the following:
Scoped Rifle (Blast 6, Improved Aim, Accurate) [14 PP]
AE: Grenade Launcher (Blast 4, Burst Area) [1 PP for 12 PP of powers + 2 AEs]
AE: AE: Smoke Grenade (12 PP of Obscure) [cost is 1 PP in the Grenade Launcher Power]
AE: AE: Flashbang Grenade (12 PP of Visual/Auditory Dazzle) [cost is 1 PP in the Grenade Launcher Power]
it's ultimately up to the GM, but I've known many of them to allow something like the above. Now if you tried to chain a bunch of items so that, say, you spent 21 PP and had a 20 PP power with an AE with a 19 PP power with an AE with a 18 PP power with an AE with a 17 PP power, etc, you'd be stomped down pretty quickly.