Which gapps cant be downloaded through the play store/marketplace?
Yes, I'm pretty sure all of the other 'Google Apps' can be requested from the Play Store. I myself, also usually start the basis of a new ROM installation with the Nano-gapps package. 

It removes a lot of the non-mandatory Google bloatware such as GoogleNow, PlayMusic (I use an alternative) and even Gmail (I have my Gmail emails come through the stock Email app to avoid duplication).