Zam zam

Q: If a little Zamzam was pored into normal water (and vice versa) will all the water become Zamzam? If so will the water continue being considered as Zamzam even if there are only a few drops in the container before normal water is added?

Q: Does the Hadith "Zamzam is for the purpose it is drunk for" apply also for a small amount of zamzam which has been mixed with tap water? Also, should we recite the dua "Allaahumma innee assaluka ilman nafia [..]" when drinking such diluted zamzam water? I am asking since I heard that the qualities of zamzam remain even after dilution.

Q: Can zam zam water be drunk with meals? Does one have to stand when drinking zam zam water?

Q: Do we have to drink zam zam water standing up facing qibla?

Q:

1. I have witnessed many Muslims standing up when they drink Zam Zam Water. Those who sit and drink are being ridiculed by many people and even Mullahs who justify that we must always stand up while drinking Zam Zam Water. 
2. I have also witnessed many people standing/walking while drinking water and eating dates in Haram Sharief in Makkah. But, the Sunnah of Rasul Allah Sallallaahu Alaihiwa Sallam is that we must always sit while drinking or eating. Please clarify in detail.