And is the consensus that using upsampling and also room correction- equalization in Roon is in fact an improvement from bit perfect mode
I am using upsampling to 24/192 when I can, and definitely a big improvement. My good DACs (Schiit) can not go higher than that and I did not see any improvement on my cheaper DACs (RPI based) when I went to 384. I am using Audeze corrections in Roon which also improves the sound, particularly with Vocal. I am not good at using Roon Parametric Equalizer, but I am sure many in this community can talk about that.
Depends on your equipment. Ideally there should be no change as the original file is the same, however, many DACs are not as good with low resolution conversion as they are with high resolution - so differences are often noticed.
Room modal correction below about 150Hz is worth experimenting with. The general rule is you should notch filter the peaks out (to even out the response) but do NOT boost the nulls. (Boosting nulls can cause amplifier clipping and possible speaker damage)
Try it out and see.