Filters

You can unscrew it by hand, there are no tools necessary. To unscrew it, rotate the nosepiece counterclockwise.
The Clicklockk is held in place with the tiny screws at the side, but the noseiece is only screwed onto the body. It is the part Baader 2" Safety Kerf nosepiece with 2" filter thread # 2408156 with a regular thread (an SC-thread).

We do NOT recommend this! No filter near focus can replace a front end blocker - as 100% of solar energy hit the filter close in front of the focus position. Front end energy blocking is mandatory for H-alpha work - but not so for white light work.

Why - because in white light you could use a Herschel Wedge Prism to throw away 95.4 % of ALL entering energy - before it even reaches the first neutral density filter or dielectric continuum filter.

This is not possible on H-alpha - you need 100% of the H-alpha wavelength, but preferably zero of anything else. so - in theory - you can do this as you describe - but the filter at that heating point can break on you any second.

Also - all photographic narrowband filters ought to be fully blocked OD 4.0 from 390 nm to 1150 nm - as this is the sensitivity range of almost all CCD/CMOS-chips (most filter suppliers though do not show their blocking efficacy above 700 nm....).

So the 3.5nm H-alpha-filter is surely blocked to 1150 nm - but our front end D-ERF-filters are blocked to 1450 nm - exactly to provide perfect solar safety. Above 1400 nm most optics do not pass IR anyhow.

The BCF1 will work.

If you have a regular 90° star diagonal instead of an Amici at the moment, the Amici will deliver correct-orientated images like in a pair of binoculars or with the naked eye.

The free aperture of this Amici is larger than that of many smaller Amici prisms which are included with some telescopes, so there is less vignetting with eyepieces with longer focal lengths, but both the C5 and the Amici have only got a free diameter of 26-27mm, so there will be some vignetting with most 2" eyepieces.

It is not possible to replace the eyepiece clamp with a Clicklock.

As 17mm eyepiece, you can use it both with 1.25" and 2" focusers.
If you remove the 1.25" nosepiece with the included optics, you have a 21.8mm eyepiece, which fits only for 2" focusers.