Re: a measuring cup, glass container & citric acid from health food store will work?

The taste isn't too bad as long as you hold your nose while drinking it. :)
But don't take my word for it. I'm still not sure my Miracle-Mineral-Supplement /activator is performing on par.

About the rest of your questions: Yes. (at least, in theory)

Note: If you have fungi, candida issues, then I've heard citric acid might not be wise to use. Others have suggested using pure lemon juice instead, if you have candida etc.

But let me stress that I have no experience with this myself.
I only am repeating what I've seen others say.