This month Loi kratong is on the 12th and then there is the funeral on 14, 15, 16. Is this correct? Are government offices and banks open on these dates?

anybody know?

Since I've been here, Loi Kratong hasn't been a public holiday and it is business as usual. The 14, 15, 16 is a tough call. I've gotten conflicting information and can't help you on that. If I hear anything, I'll be happy to post.

I am always amazed at the lack of information about what is open/closed on events like this. I am also surprised that places don't know if they can serve alcohol or not.

It's a bit like Songkran, really. Many years ago, it was only a one day thing, but obviously there was too much money to be made from it. These days, most hotels even bump the period up for accommodation charges. So expect Loi Kratong to be bumped up in future years to a higher than normal season price (now three days in most places, but I believe five days in BKK) - up from one day not all that long ago. Little wonder there are so many different festivals, etc in LOS - mainly baht driven.