One may try to start to give some answers, in hoping the some other colleagues will soon do much better.
It would be well if you did have the French language.
"French Napoleonic Cavalry form by fours, twos, or both, as required"
It is "as required". Habitually, when moving with the army, the horse, especially the light horse did not use the roads.
Let us have some back ground may be :
A régiment will be composed of 2-5 escadrons (3 and 4 were most usual). One escadron is typically that of the dépôt, and will not be with the others (although these can be grouped and sent in to a campagne as régiments provisoires).
Each escadron will be composed of two compagnies. In the ligne cavalerie, two escadrons will be commanded by a chef d'escadron (not "d'escadrons, until the restauration). The compagnies will be kommanded by capitaine. The compagnies may be referred to as "pelotons" in drill manuals and discussions of manvres. In truth, they are compagnies in the period 1800-1815. For the hussards, the best hussards will be sent into the 1ère compagnie, called the compagnie d'élite, and will wear the kolpak. There will be a rough seniority of the other compagnies, by the seniorities of their capitaines, but this will not be too pure especially at the end of a campagne. There is no equalization of the compagnies nor ranging of the men by size in a compagnie, so far as I have never once seen it mentioned as actually beign done in the cavalerie légère of 1800-1815.
A compagnie will always form in two lignes. No matter what other thing is done, there will be two lines of hussards. Even in a column of 2's, the fornt and rear ligne will be seen to be in each two and the next two behind them. It is not unknown that the two of a fil will be "comarades de lit" in caserne – the beds were made for 2 men in some cases.
The strenth of a compagnie is typically 90-100 hussards, but they will be smaller to 70 or 80 and may be 120-130 at full strength. With 100 hussards the compagnie in line will be 50 fils in width. The régiment with 3 escadrons in the field to gether will number some 600 hussards.
One half of a compagnie is a peloton or demi-compganie : 25 fils
One-half of a peloton is a section or an escouade : 12 files.
To move across the country, the régiment will form a column of pelotons or of sections most often. The column of 4's and 2's would be to pass an obstacle. So, with 3 escadrons, or 24 sections, the movement in column of sections will be 12 fils wide and 48 rangs deep, plus gaps for each compagnie and escadron.
To form on the battlefield in a column, the mose usual will be a column of escadrons (100 fils x 6 rows) or compagnies (50 fils and 12 rows).
But any other column could be formed.
The formation of the compagnies will be some thing like this
1er escadron : company d'elite and 4e compagnie
2e escadron : 2e compagnie and 5e compagnie
3e escadron : 3e compagnie and 6e compagnie
4e escadron : 7e compagnie and 8e compagnie (dépôt)
1er escadron : company d'elite and 5e compagnie
2e escadron : 2e compagnie and 6e compagnie
3e escadron : 3e compagnie and 7e compagnie
4e escadron : 4e compagnie and 8e compagnie (dépôt)
We will then see a column of compagies formed normally :
Ordre inverse is with the 6e compagnie in front
The manuals will re-number these 1 to 6 pelotons. I have never seen any actual usage of this for the cavalerie 1800-1815. The manual were wriiten, one suposes , by analogy to the infanterie. For these, it was needed to equalize the compagnies and the rangs (2 or 3) were all the same – a musket for French. In the cavalerie, the rangs may be different (lance and carbine). And there is no square, etc.
"It talks about forming line on the left if your front is at the rear".
On will want a way to go from any column (normal or inverse) to a line formed with the compagnie d'élite on the right or on the left and with the facing either the same front as the column, at some angle to this front or facing the other direction. Thus there wil be many specific drills.
Then each of these will need to be run the other way also, to create a column from a ligne.
"dressing by size"
I do not know it have actually occurred among hussards. Actually in a section, a command for a sous-officier, of some 25 hussards, there wil be 3-4 "ordiniares". These are groups of men who will cook in common and split up the work of the horses, the finding wood, etc. They will aslo look to each other in a battle and re-form together after a formation is broken up in a combat. To move them around for size would not seem a good idea.
"right dress could be a time consuming"
The question of dressing, especially of close dressing knee to knee well-aligned is commonly mentioned for the cavalerie lourde. It is done and re-done by the officiers and sous-officiers. But for hussards, I do not recall it being such a fetische, or more likely the hussards did not have to stand and wait so much and thus did not have some much time to hear the counsels of their fears.
One will have no corporals, but rather brigadiers
a maréchal de logis is like a sergeant
a maréchal de logis chef is like a company sergeant major (one per compagnie)
"he drill manual mentioned that farriers would be deployed behind the second squadron. "
The French did have one or more maréchal ferrant. He is often not actually listed in the ordonnances, eespecially for hussards. He then did not get an extra pay. But, in a régiment there will some smiths, and these will do this work, and get a little fee from the officiers to work on thier own (private owned) hourses. He may be will have a little insignia on the upper sleeve. In dragons, the position is more formal. In any case he is a hussard or dragon regularly, and takes his place in the ligne de bataille.
There is usually no field forge, and the ferrants did just take over a local smith's place. In Poland and for Russia, the field forge was needed.
There is also a kind of clerk in each compagnie , called a fourrier . He is a brigadier with extra pay and sees to the lodging of the compagnie, its supply, its pay, etc. He will form among some other sous officiers behind the second rang (other sous offciers will be in the rangs). In a parade, the fourriers will form with the aigle of the régiment.
"The Regimental craftsmen did bear full combat responsibility"
These will be at the dépôt in most cases, to work on the equipment. Some may take the field, and will form with the régiment headquarters.
Required in dragon and lanciers (and a pocket in the saddle for them). One suposes that hussards would be wise to have them also.
OK, it is a start, one may hope,