Yes. I'd recommend a pignose adapter that clamps around *both* the top and bottom of the head tube, that is much stronger than a skinny clamp on just either. The clamp diameters may be different for steel versus aluminum frames, yours is steel. I think there are choices of adapters that have the rack interface vertical, or laid back slightly to be parallel with the head tube. The one drawback I have seen on some adaptors is only rack contact on a narrow strip, versus the mounts on Brompton IIRC, are v-shaped and contact the head tube on each side, for better lateral stiffness so the rack doesn't wobble laterally or fatigue the mount.

Another option on a Speed is a small brake-post rack, they are perfect size for the application, sometimes called a Sixer rack because that size. I'll try to find a photo of mine. I've modified the rack with an additional stick to keep panniers out of the spokes, and hung smaller panniers there. I've also hung a small backpack from the handlebars with the shoulder straps, but that would not go on and off easy, I needed quick release buckles for those straps. That little brakepost rack is strong, and I've hauled huge parcels and purchases there, tied to both rack and tall handlepost, that huge available space makes a 20" wheel bike a tremendous cargo bike. Loads on the (fork) rack are steered mass, calms steering but feels weightier; When front panniers loaded, I put heaviest things inside them aft, so behaves more like lowrider front racks centered on fork. Loads on a pignose rack are not steered, however mass there (forward of steering) also improves stability, it improves the (already existing) tendency for the bike to steer in the direction it is falling laterally, according to a detailed study on bike stability.

I just bought a disc Dahon, won't be able to use a brake post rack, I'll need a conventional one, preferably sized for 20"/406 wheels. Or use the pignose on that frame, but it's aluminum, so I don't want to cantilever too heavy a load too far forward on that, I like to be conservative with regard to frame stresses.

EDIT: Water bottle: Yeah the stock Dahon mount on the top of the main tube, don't do, it won't be long until you hit it with your foot and bend the bottle cage. Plus full bottles leak when horizontal. OH, you don't have those mounts like mine, no loss! Options: Notice my water bottle held by my aero bars, proprietary design on both. Without aero bar, I would put a cage mount near the top of the handlepost, they make cage mounts to fit that. Could also do front or back of seatpost, or back of seat, they make cage mounts that attach to the seat frame, can hold 1 or 2 bottle cages. You'll need to experiment to see which works best if you fold the bike a lot. Back of seat, if clears the rear rack when seatpost down, may be best.

Kickstand: Single side stand will work fine, provided its length matches your tire size well. (Me going from stock 1.5" to 1.75" tires, meant I needed a touch taller kickstand than originally.) It also helps to turn the front wheel toward the drive side, counterintuitive, but the bike may be more stable, mine is. They make double-stands where both legs retract to the non-drive-side, a little pricey but I've heard they work well as a center stand, but deploying the stand and wheeling the bike back onto it, will raise either the front or rear wheel, might stay off the ground if stand not trimmed perfectly. But better it be a little too long, than a little too short, the latter and it just functions as a single stand.

Pics: whole rack setup, better view of front rack (on shuttle bus), bike folded on train car luggage shelf, cargo: rollaboard suitcase, cargo: medium sized cooler.