Polarizer & Neutral Density

If your optics is so well color corrected that parvocality only means to keep the filter thickness the same as befoire, then indeed the new CMOS-optimized filters are parfocal to all Baader-filters as we try to keep the substrate thickness consistent troughout all our filters.
Otherwise we want to confirm that the new CMOS-optimized filters are on a much higher level of coating technology compared to the previous ones.

Yes this filter fits in 6D I

The telecompendium has a 2" thread inside on the telescope side, into which a 2"/T-2 reducer is screwed. If you take this out, you have a 2" internal thread and can screw on the TZ-3 directly. In addition, the focal point of the telescope is approximately in the center of the TZ-3.
Therefore the beam at the entrance of the TZ-3 is very narrow and fits through the 25mm opening there. Only in the TZ the beam path is widened and parallelized so that even a Halpha filter with 46mm free aperture is fully illuminated.

This can be done e.g. with:
Baader 2" Safety Kerf nosepiece with 2" filter thread # 2408156
Baader UFC S70 / 2" SC-thread (f) Telescope-Adapter (optical height: 1 mm) # 2459128
Baader UFC Base (Filter Chamber) telescope-sided S70 dovetail receptor (optical height: 13 mm) # 2459110
Baader UFC 2" (m) SC Camera-Adapter (optical height: 2 mm) # 2459120
Baader 2" ClickLock SC/HD (2") clamp (C5" - C9¼") (optical height: 47 mm) #2956220
Please note that this will add 63mm to your focuser. At a Newtonian which has got an extension to reach focus with eyepieces, you need to remove this extension; it may work. Please check the focus position of your telescope to find out if you have at least 63mm of backfocus available when you remove the extension.

You could also use
Baader 2" Safety Kerf nosepiece with 2" filter thread # 2408156
Baader UFC S70 / 2" SC-thread (f) Telescope-Adapter (optical height: 1 mm) # 2459128
Baader UFC Base (Filter Chamber) telescope-sided S70 dovetail receptor (optical height: 13 mm) # 2459110
Baader UFC M48 (m) Camera-Adapter (optical height: 2 mm) # 2459116
Baader 2" ClickLock M48i clamp (2" filter/photo thread) (optical height: 36,5 mm) 2956248
which would be about 1cm shorter, but then you are limited to eyepieces with shorter nosepieces (about 30-35mm).

If possible, you should remove the 2"-clamp of your telescope - maybe there is a thread belwo, to which the UFC can be attached with a matching telescope adapter. Unfortunately,, we do not know that specific telescope and do not know if tehre is a thread and which dimensions it has got.

The eyepiece will work very well with your telescope but we cannot guarantee how good the image will be with GSO Barlow attached, we never tried this combination