1. Actually that makes no sense, using a fan at the highest setting would just speed everything up. When you have Acetone and you want to evaporate it, then using a fan on high will draw a lot of water in your acetone, so that would not be too good. Still using a fan with lower settings will take much longer, so still much water from air moisture will be drawn into that Acetone. For Naphtha that will not happen, so it does not make any difference.
Also no worries for oxidation with your DMT. If you fan it super high for 15 mins nothing will happen and I may say even for hours it wont damage it. The oxidation occurs like this:
UV-light energizes Oxygen and forms Oxygen radicals. This can only happen in well lit areas, where a certain volume of the room air is touched by direct sun rays. Now if you would stand your DMT in a dark corner of your room and use a fan to blow air above the DMT, it may draw air from the well-lit areas onto your DMT and oxygen radicals may touch the DMT. But then if you have a totally dark room, then the amount of oxygen radicals in air is negligible. This way you could fan your DMT for ages and it wont be too bad. Still, why not just place your DMT in a dark shelf and just wait for 1 h ? It's the same, you just want the last residual Naphtha to evaporate and this also works without fanning, just wait a little longer. When you dont smell any Naphtha, you are done and you can scrape everything.
2. You talk about going from a desired temperature to room temperature - so you mean you want to cool something down. But at what step is it crucial to cool stuff from your acid/base stuff?
Besides I would not use a water bath and just place the container with your material on the stove. If you check out what settings you need for the correct temperature, then you will just use that setting for the rest of your life and make things easier. Naphtha would only ignite above 220 °C. Obviously you will never heat your stove to a temperature like this, so people telling to not directly put a Naphtha container on a stove are a little bit over-acting

In any other case, the Molecules wont care how fast / slow you heaet something up or down. DMT is not heat sensitive, so you would not trigger any decomposition routes by conducting a step too fast / too slow.
3. Normally these crystals should mostly form at the surface of the Naphtha where you find the Meniscus or at the bottom. I cant see why regular coffe filter should be bad, if your product is rock solid then you can collect it easily without it sticking anywhere.
4. I cant see any benefits from that, as you already got rid of all your Naphtha you wont change anything with your final product. What may even happen is that there will be water condensation from the air moisture at your DMT crystals, which will then stick to them when scraping them off. This cant happen if they are covered with Naphtha, but may happen when being exposed to air with higher temperature. So I cant see any use for this