Yes, you can go there any time for your convenience. No free access to the panadas, you need to pay for it. My friens paid RMB200 for holding a little one. The best time to visit it is 08;00-10;00, when the panadas are have meals and doing some performances, also there are not too many visitors during the time.
The nearest hotel to the Center is Chengdu Meili Conference Hotel(成都美丽会议酒店）. It's about 7 kilometers from the center.