My apologies! I've been a bit wrapped up in other things and haven't shared this information. Ticket sales started noon on 16 June. Tickets go very fast, so if you want to see something, please check out the website ASAP.
The free concerts should be good, weather permitting:
The website (English version): http://www.taipeicaf.org/News/NewsContent.aspx?id=4838&NewsID=564