Smoke friendly places are all over in himachal. Well you still have to watch out for the police etc, but charras is all over. Although august / september is a bit early for fresh charras.
Go to the parvati valley, just (well 3 to 4 hrs) off Kulu. Don't expect to find beer easily though as it is a traditional hindu area, where it's not easy to find meat, let alone alcohol, unless you can stomach the white "rum" (not rum at all really... they call it "wine" too) that some locals drink. I can't.
Bhang shops yes, you'll find some in Benares/Varanasi. (there used to be a great one on one of the big roundabouts on the main street leading to main ghat). There are official government bhang shops, as well as bhang lassi "bars" (well not really bars but you know what I mean)
As for goa in september, the atmosphere is still very damp and the sea isn't very clear at that time of the year, but I spent a month there in september a few years back and I don't think I saw any rain at all.
The only problem : 3 weeks it much too short a stay for india. Takes you a month or two to get used to the place