Deciding on the headgear is a bit prickly. WF can follow the original mission and make the sprue as generic as possible from 1690 to 1720 with only floppy hats and tricornes, or they can try and accomodate some or all of the various "odd units" out there. The Queen's Dragoon makes a very good suggestion above that his pictures support. If the figure is generic enough it can be made to work as the bulk of the Horse and Dragoon regiments present. However, there will be compromises.
1. Many Dragoons wore gaiters instead of boots.
2. Most Dragoons wore their sword from a waist belt while most Horse wore their's suspended from a shoulder belt worn over the right shoulder, suspended on the left.
3. Dragoons could be depicted with their full-sized musket in one of three positions: (A) Holding it in their hand; (B) Slung over their shoulder using the musket's sling like an infantryman, or; (C) Slung from the shoulder belt, butt down, as depicted in the picture above.
4. Horse, depending on the nationality and sometimes the specific unit within a given nationality, should be depicted with a shorter fusil or carabin, and could be depicted with it: (A) Suspended from a shoulder belt muzzle down and loose; (B) Suspended from a shoulder belt muzzle down with the muzzle resting in a leather boot attached to the saddlery, or; (C) Simply left off, as not all Horse in all nations carried long arms at this point, relying on just sword and pistols.
How we deal with numbers 1 and 2 will be where we, as gamers/painters have to make compromises. How we deal with numbers 3 and 4 can be aided by the design that WF comes up with, which is why I agree with the Queen's Dragoon's post above.
Now, as to headgear and depicting the more unusual units:
1. You would need a true Grenadier's tall mitre for British Horse Grenadiers, the 2nd Royal North British Dragoons (Scot's Gray's), and Grenadier companies of some Dragoon regiments.
2. You would need a fur-fronted and banded stocking cap to properly depict some French Dragoons or the Grenadiers a Cheval of the Maison du Roi. See Eugene Leliepvre's excellent plates from "le Cimier" on these units here.
3. You would need a stiffened cloth short front (like a short mitre) on a stocking cap to depict other French Dragoons and Dragoons of some other nationalities, and the "bag" of the cap could be suspended down in back or down on the left side. Again, reference the Dragoon plate by Leliepvre here.
4. You would need a shorter version of the Infantry bearskin with a bit of a peak or point at the front to depict Caribiniers and Horse Grenadiers of some Germanic nationalities. Although from a slightly later period, you can see this type of headgear here.
And, it should be noted, none of the above addresses the quite useful Bavarian and Imperial Cuirassiers who still look more like a late ECW Lobster than anything else, wearing a leather buff coat and European-style lobster pot helmet. Nor does it address those Horse units that typically wore the coat open with a breastplate or full cuirass underneath.
And, as to artillery (agree, it should be a separate thread), the amount of artillery models and crew will vary greatly depending on the rules used. I will need many more to play at 1:20 than someone playing BLB with 18-fgure battalions or the new "Le Roi de Soleil" supplement for "Impetus" with 12-figure battalions. Most field artillery will be grouped into one or more "grand batteries" and not likely to move about during the game, while Infantry battalion guns will be prolonged by their crews after initial deployment. Also, the battalion guns were usually at least partially-crewed by Infantry drafted from the ranks and the field artillery were often supported by pioneers who would look essentially like Infantry.
All of the above, both on the Cavalry and the Artillery, supports (I feel) the need for a separate Head and Accessory sprue (which I have called for previously on the Infantry thread). All of the various unusual heads listed above, as well as bare heads and the more unusual Infantry heads (karpus anyone?), could be accomodated on this sprue. Along with the heads could be included some various Artillery implements, perhaps another torso for the multi-part Infantry figure appropriate for someone detailed to support a battalion gun or a pioneer, and perhaps a few more sidearm options for the folks that prefer making diorama's out of their unit stands with maximum variety, and finally a torso in long waistcoat and no outer coat which would work for not only artillerists and pioneers, but would be perfect for Russians in summer dress and French operating in the Colonies. This latter torso could also be used to depict militia in North America as well as the European regular troops.
Sir William the Aged