Greybeard

Sounds like you have activated Bracketing. See the manual here for the Drive/Delete Menu http://fujifilm-dsc.com/en/manual/x100v/about_this_camera/parts/index.html#drive_button

I don't understand your argument. Surely all this says is that you cannot have IBIS only if you have a OIS lens. It doesn't say that IBIS has no effect with an OIS lens and OIS turned on.

Example? Maybe provide a link to an original file straight out of the camera.

Adobe already supports X-T4 raw files. https://helpx.adobe.com/uk/camera-raw/kb/camera-raw-plug-supported-cameras.html (But to answer the question - there is a new type of lossy compressed raw for the X-T4 in addition to the lossless compressed available with the X-T3)

I have used the ProGrade card on my X-T3 and been happy with the results. The only curious problem I had was in mixing SanDisk and Prograde UHS-II cards in different slots. So based on that experience I'd get two copies of the same card. (Even for the X-T3 the specific card recommendations from Fuji were outdated)

I've found setting it to AF-ON to be the perfect solution - the button is just the right location when you want to activate AF manually and I've never come across a situation where activating it accidentally caused a problem.

Do you mean the FujiFilm leather case: https://shop.fujifilm.co.uk/fujifilm-x-t10-t20-t30-leather-half-case It is being sold as suitable for X-T10 and X-T30

Haven't seen any rumours and it definitely isn't on the list of changes published by Fuji. Its not on the X-T3 either.

Presumably the camera works OK with other lenses? (Which implies the lens is the problem). What are the pictures like? Does the lens communicate with the camera (focus, aperture, metering and EXIF)? Do the contacts look OK?

How are you measuring the bitrate? If a video clip which takes 5 seconds to shoot at 200Mbps is played back at 4x slow motion (i.e. 20 seconds) then the average bitrate over 20 seconds will be 50Mbps.

Exiftool is almost always the answer for metadata and I use it daily - but if it doesn't meet your needs for video I'd take a look at Mediainfo which sometimes does a better job of actually analysing the video streams - its also multiplatform (even iOS!!)

Does the flash have an AF Illuminator - have you looked in the flash menu under LED Light Setting? (I think Silent Mode was dropped from recent Fuji X cameras)

Why do you want to remove the warning? It might help those who wonder why they can't choose a slower shutter speed than framerate and haven't read the manual.

You'll get a lot of different opinions as to the "best" option unfortunately. Its going to be a balance between how much you want to pay, how much you are willing to learn new software and whether each option provides the functions you want. There are some who have had trouble with processing Fuji X files with Lightroom - if that is a concern you might try the Adobe DNG raw converter route for a while and see if you like the results.

How about upgrading the Adobe software?