About (1), the diagrams in this post might be helpful. “OutputPass” refers to the three.js effect composer, not the pmndrs postprocessing library, but if you replace that with pmndrs’ ToneMappingPass, the diagram looks the same.
i had a red object blooming, but the tonemapping turns it into a light red/orange color.
This is expected. Tone-mapping desaturates colors (especially those with RGB values >1, but also values within [0–1]) as it forms an image from scene lighting information. If you can, I think the best approach is usually to allow the desaturation to happen, adjusting original colors, exposure, and perhaps tone mapping to create the final image you want. Consider the images below.
Without tone mapping:
With tone mapping:
The lightsabers desaturate to white with tone mapping, and as the (less bright) areas around them keep more of a saturated red color in the image, this is how bloom and tone mapping are usually intended to work together. I don’t meant to say you can’t choose something different… but just want to be clear about why it works this way. 
I do feel that ACES shifts the hue more than you might want, though, this is a bit of a known problem. We’re working on providing better options than ACES Filmic, like AgX tone mapping from Blender 4.0, see the discussion here:
Can someone guide me through how i should set these parameters in order to get the “ACESFilmic” tonemapping that threejs usually does?
I’m afraid I don’t know about these, perhaps someone else can weigh in. Personally I don’t think they’re hugely important. Contrast and exposure are the more common knobs to adjust.