I have the following:
DD MK18 upper
LMT Lower with SOPMOD stock
Surefire SOCOM556-RC can
Adjustable gas block

I need input on an optic.
---> I'm leaning towards the Aimpoint Micro T-2
...what mount should I get if I get the T-2?  
...Samson skeletonized qd mount?

I need input on a light.
---> Surefire? Inforce? Klarus? Oveready?
...IR? How many lumens is too much?

Besides the above, any other suggestions? P-mags? E-Mags? GEISSELE S3G trigger? Battle Arms ambi-safety? H-Buffer? Bad lever? PRI gas buster?  Cool bag for the range? Back up irons? Tango Down stubby vertical grip? ...OK..so maybe I'm not 90% done but I hope to be soon  with your help.

More info than you actually need.

buy ammo,,

If your not worried about impressing the Kool Kids...
Mags: Pmag or USGI. They have a history of working. Can get D & H for as little as $7 or less on sale.
Ambi-safety: Standard DPMS style you can get from almost any AR supplier for about $30. It works.
Most of the rest is personal preference and how much are you willing to spend.

BAD-ASS
SSA
Pmags
T-2 in a Larue
Scout 300m