BACHES Echelle Spectrograph

No. A dustcap is not included with the Rubber/Metal foldable Morpheus eyecup.

The Contrast Booster is ideal for observation of moon and planets for Fraunhofer refractors with short focal legth, means big colour abberation when magnification is high. It is not best for nebulae because these get not observed with high magnification so the colour abberation is not visible. The filter is furthermore not necessary for mirror telescopes like ACF because these have no colour abberation. If you want to observe nebulae with an ACF telescope you should choose an UHC-S filter. For planets choose the Neodymium filter or colour filters, especially on Mars colour filters (orange for surface detail, bright blue for clouds) are enhancing contrast massively.

Unfortunately the AVX has another foot than AS-GT and other mounts, therefore this adaptor will not fit.

We do not know this specific telescope, but you can find it out yourself: All you have to do is measure the backfocus of your telescope. How to do this, is described in the manual of the binoviewer on page 4 and 5. In general, you will need a glass path corrector to reach focus - which one, depends on your available backfocus. You can find the manual here:
https://www.baader-planetarium.com/en/downloads/dl/file/id/154/product/1265/instruction_manual_for_baader_maxbright_binocular_viewer.pdf

This usually works - both Celestron and Meade use the same SC-thread. So, the thread should be the same, although we have made the experience that in the past there were some Meade-telescopes where threads were so far away from the tolerandces that it didn't work. But usually the threads should fit.
Depending on the depth of the thread of your star diagonal, it may be that you need an additional spacer, otherwise a coupling ring may rotate, although the threads fit. Unfortunately, we do not have Meade accessories here to try it out.