New 6.5 grendel build help!

[buckbustn]

Hello all,
I am new to ar platform builds and have decided to go with the 6.5 grendel. Sorry if my questions seem stupid but bear with me please.
I ordered the Alexander Arms 24" Advanced Weapon System - Complete Upper Receiver and purchased a stripped CMMG multicaliber lower from a local shop.
I plan on fitting it with a Magpul prs.
Being new to these builds, here goes the questions.
Will the "complete" upper come with charging handl, bolt, and carrier group?
What parts do I still need to purchse?
The lower parts kit I buy, do I need large pin or small pin?
Do I need to buy anything special to fit the prs?
Any help, suggestions, or a list of what I need would be greatly appreciated.
Thanks!

[Drifter]

Will the "complete" upper come with charging handl, bolt, and carrier group? Yes, it should.
What parts do I still need to purchse? Accessories such as sights and / or optics, sling, etc.
The lower parts kit I buy, do I need large pin or small pin? small
Do I need to buy anything special to fit the prs? I think you'll need an A2 buffer tube, buffer, and spring (unless you're buying a complete kit that already includes those items).

See answers in red above.

[MrDraco]

And make sure the buffer tube, buffer and spring are all rifle length. You do not want Carbine length parts as those are designed for collapsible stocks.