I was recently there in October and leaved the first day when it started to rain heavily in Hua Hin.
I can not recommend HH city itself like this (city beach is a total crap), but just find a hotel south to HH - beach is called Khao Takiab - it is very popular amongst locals and gets crowdy on weekends. This means also that some Thai language knowledge is warmly recommended - and I do not have this knowledge, but still managed somehow
Answers to Your important questions - I was there with my missus from Estonia
, so not so much comments about ST either LT prices, etc...
There is some bar action of course in HH, and much more are seen really "mid-aged"
farangs walking on streets around with young TG compared with Phuket scene.
But anyway relaxed and nice place - and what is the most important thing IMHO - when it rains in Phuket, it does not rain in HH and vice versa.
This fact I will take into account when planning my next year trips to LOS.