Yo, you can do the trek through TLG and end at Tinas Guesthouse. Youll have to inquire at Tinas or Halfway GH about getting a guide to take you all the way up to Haba Village. The hike from Tinas takes 8 hours or more to Haba and there is nothing in between. The road that goes through TLG continues to Haba Village, so you could hitch it instead. You can rent equipment in Haba Village and climb to the top of the mountain with a guide as well. Its high, but not technical. Anyone in good shape can get to the summit (assuming good weather)
Any hiking store should have them. Check the shop with the giant backpack near Wenlinjie. If they don't have them, there is a shop on Beimenlu (about halfway between 121 street and Yuantongjie) that definitely sells them for 20RMB per cannister. The shop is small but it is located on the north (zoo) side of the street.
The best hiking store in town is Mei Li Outdoor Sports. They have everything you need. Its all name brand top quality stuff, so its not cheap. Its between Qing Nian Lu and the XinXiNan Shopping Mall on Huguo Lu. Its pretty large and the sign is written in English and Chinese. They definitely have propane and stoves. The shop on Beimen Lu also has propane and stoves and that place is cheaper. Why not go there? I bought my tent there, too.