I don't know the answer to most of your questions, but I have a couple of thoughts. Recipes I've seen and what I've followed, is to strain out the solids after 2-4 days, and let the liquid continue to ferment to your taste preference. I would not try to use already fermented pineapple. That initial smell is probably the pineapple...my first time fermenting pineapple, I thought for sure it was going to be nasty, but it does go away. As for the bitterness, I would be suspicious of the chili powder, or the cinnamon maybe. Whole spices are probably better, like cinnamon sticks. My recipe uses that plus about 4 or 5 whole cloves, I think. Chili sounds interesting, but I think I would throw in whole fresh peppers, or remove seeds and stem. Ginger wouldn't be traditional, but I don't see a problem with it. Using the piloncillo sugar, or brown sugar not only provides the alcohol source but also flavor...if you don't ferment your Tepache to jet fuel stage. I have bottled mine before and I can tell you, it carbed much faster than I expected. I was using regular beer bottles, though...never had experience with PET bottles...but mine seemed about right in about 36 hours, I think. I am, by no means, an authority, but that's my two cents, for what it's worth. Oh, and a small (2-1/2 gallon, I think) fermentation bucket and an airlock would be cheap, but handy additions.