Salam Yahya
The thing about the drinking, there is no mention of that happening in the Quran, so it is highly doubtful that the prophet used to lash people for drinking. Since, it is not mentioned in Quran, and none of us witnessed it by ourselves, we cannot say this used to happen. If, this practice is carried out today, then this is done because of injunctions present in other sources but not in Quran, but so do muslims of today do other things like stoning for adultery, killing of apostates, prayers not accepted for 40 days for drinking etc . All these are practices/ believes that are practiced today in muslim countries but do not have a Quranic injunction. I am not sure what do u want to know? But, if a belief/practice is not mentioned in the Quran, muslims are not required to do them, but muslims do these because they follow other sources besides the Quran ( hadith, sira etc) that are not sanctioned or have any religious authority according to the Quran. The Quran is the sole source of religious guidance for believers. Please read the relevant artice on the website by Brother Joseph.
http://quransmessage.com/articles/quran%20sole%20guidance%20FM3.htm