That performance of the compression meter is normal for those compressors… in fact it’s a design feature, it’s part of the design of the compression characteristic that the compression release time extends out towards the end of the release.
The sub-sonic filter just switches in a filter to reduce the amount of very low frequencies in the audio…. it’s useful when recording voices, It minimises noise transmitted up the mic stand from the floor!
Only a few of the bricks made had the ‘VC1’ designation on them…. most did not, in fact it was the later ones tht had ‘VC1’.