So this is a peculiar question which I am not sure what the answer is. I have Yacreader setup and everything is working as intended. I can read comics via wifi with my iPad mini when yacreader is open on my Windows computer.

So my question is, can I read comics that I have stored in let's say Dropbox through my iPad without having to download it first onto my iPad. I want this because otherwise I have to keep my computer on, if I want to stream it via wifi from my computer. I would like to read my comics that are stored in Dropbox without having to download them.

No, you have to import them to the app first.

Time ago a was able to compile YACReader in a Raspberry Pi, I think that having a little Pi for serving your comics library can be a nice thing in a home network.

I will try to release a final version for the Raspberry Pi.