OK, as requested.  Differences are in bold.

Option 1 (Any)

Non-square figures may move one space in any direction, exactly like a square figure. They may also rotate 90 degrees while continuing to occupy as many of the same spaces as possible (1 space for a 1x2 figure, 4 spaces for a 2x3 figure).

Option 2 (Long)

Non-square figures may move one space in any diagonal direction, or along its long axis ("forward" or "backward", but not "sideways"). They may also rotate 90 degrees while continuing to occupy as many of the same spaces as possible (1 space for a 1x2 figure, 4 spaces for a 2x3 figure).

Option 3 (Long/Any)

Non-square figures may move one space in any diagonal direction, or along its long axis ("forward" or "backward").  2x3 figures, but not 1x2 figures, may also move along their short axis ("sideways").  Both 1x2 and 2x3 figures may also rotate 90 degrees while continuing to occupy as many of the same spaces as possible (1 space for a 1x2 figure, 4 spaces for a 2x3 figure).

Option 4 (Long/Short)

Non-square figures may move one space in any diagonal direction.  1x2 figures, but not 2x3 figures, may also move along their long axis ("forward" or "backward"); 2x3 figures, but not 1x2 figures, may also move along their short axis ("sideways"). Both 1x2 and 2x3 figures may also rotate 90 degrees while continuing to occupy as many of the same spaces as possible (1 space for a 1x2 figure, 4 spaces for a 2x3 figure).

I think that covers every option that has been seriously discussed in any thread I've ever read.  If we try to cover every conceivable option, seriously discussed or not, we'll probably never finish.

Antistone said:

I can live happily with those answer options, as long as you now frame them with an actual question (and preferably a preamble). You are welcome to use copy my preamble and/or question directly, or rewrite your own.

Corbon, the bold in your last suggestion did alleviate some of my concerns. If it's obvious at a glance where the background info ends and the question begins, that should help avoid confusion and hopefully make the preamble more of an aid than a distraction. I thought the note at the end was also a nice touch, though brevity is essential in such a note.

After reading that note at the end of your suggestion, I agree that a significant postscript would probably be ignored. I was just brainstorming ideas and don't mind admitting my suggestion was not a good one.

Antistone, I'm fine with the wording in your latest answer suggestions. There are some minor grammar issues to clean up before it's finalized, but that's really just my own OCD.

mahkra said:

Ok then. How about this?

[potential send to ffg]
Problems remain with the movement of non-square monsters.
DJitD pg15
Hellhounds and Dragons are oddly shaped occupying two and six spaces, respectively. They must move in one of the following two ways:
1. The figure moves one half of its body into a non-diagonal adjacent space while the other half of its body moves into the space(s) that the first half just vacated
2. The figure moves to a diagonally adjacent space by moving both halves of its body in the same diagonal direction (also called “sidestepping”). Both types of movement are illustrated in the diagram on page 17.

The recent FAQ instructed us to follow the diagrams on pg 17. Unfortunately, the three diagrams on pg17 show us three possible ways of moving. However it is not clear that these are the only possible ways of moving (indeed, it is fairly obvious that they are not as both dragon and hellhound can surely(?) simply move straight forward) and so it needs to be clarified what other ways are possible and what are not.
Rotations are fairly clear, but translations are not. Neither diagram on pg 17 shows an orthogonal translation (along either the short or long axis). If we go by the rules on pg15 then 2x1 monsters may translate along their long axis, but not their short axis. However 3x2 monsters may translate along their short axis but not their long axis (which means they may never move along a corridor!)
If we go by the diagrams on pg 17 then no translations are possible except diagonal!
What is needed is clear indication of which translations are possible - and which are not. Below is the question an a selection of possible answers for you to choose from.

Q. Which moves are possible for an oddly shaped monster, and which moves are not possible?

A1. Non-square figures may move one space in any direction, exactly like a square figure. They may also rotate 90 degrees while continuing to occupy as many of the same spaces as possible (1 space for a 1x2 figure, 4 spaces for a 2x3 figure).

A2. Non-square figures may move one space in any diagonal direction, or along its long axis ("forward" or "backward", but not "sideways"). They may also rotate 90 degrees while continuing to occupy as many of the same spaces as possible (1 space for a 1x2 figure, 4 spaces for a 2x3 figure).

A3. Non-square figures may move one space in any diagonal direction, or along its long axis ("forward" or "backward"). 2x3 figures, but not 1x2 figures, may also move along their short axis ("sideways"). Both 1x2 and 2x3 figures may also rotate 90 degrees while continuing to occupy as many of the same spaces as possible (1 space for a 1x2 figure, 4 spaces for a 2x3 figure).

A4. Non-square figures may move one space in any diagonal direction. 1x2 figures, but not 2x3 figures, may also move along their long axis ("forward" or "backward"); 2x3 figures, but not 1x2 figures, may also move along their short axis ("sideways"). Both 1x2 and 2x3 figures may also rotate 90 degrees while continuing to occupy as many of the same spaces as possible (1 space for a 1x2 figure, 4 spaces for a 2x3 figure).

A5. Something else (please specify)

Notes: A4 strictly follows the RAW and diagrams - but dragons and ice wyrms cannot move along corridors. A1 to A3 are other possibilities. A5 is left for you to fill out if there is something completely different we missed. [/[potential send to ffg]