I haven’t been in a couple of years, so perhaps others can provide more up-to-date information, but I considered Huashan like many Taiwanese attractions: pleasant enough if you can get there on a weekday, not worth the crowds you’d encounter on a weekend. Plenty of stalls selling mildly interesting stuff from local artists and producers, but I always feel a bit weird about those sorts of places because I basically don’t. buy. stuff. “Hey, cool idea! Nope, not going to give you money for it.” As much as anything I liked it because it’s a nice area that isn’t department-store-sterile or scooter-everywhere-noisy, and those are sometimes hard to come by here.
Treasure Hill is a similar set-up, on a nice location overlooking the river - perhaps 15 minutes walk from Gongguan MRT station. I think that’s new in the past five years or so. If I recall correctly, Huashan has better food options than Treasure Hill. (Have you been to Vancouver? Both Huashan and Treasure Hill are a little like Granville Island without the food market part. Same basic idea of renovating an old area, preserving the style, and turning it into a pleasant place to visit.)
I’ve heard good things about the Kavalan tour in Yilan, but haven’t gone on it myself: I remember once looking into it when I was in Yilan for something else, but it was an inconvenient distance from the train stations so I couldn’t fit it in that day.
For beer, have a look in this thread. Others here have recommended Redpoint Taproom, but it suffers a common problem for many of the interesting-to-drink-at places in Taipei: it doesn’t open until late afternoon (5pm). Of course this won’t matter for most people, but usually if I’m in town it’s mid-day, and I’m back in Danshui for the evening.