p.1 #2 · How to mount a speed light onto an ArcaSwiss plate?
Wimberley has a bunch of flash stuff to connect to A-S mount. https://www.tripodhead.com
The M modular system is great. You can build practically any setup you want with the right parts.
p.1 #4 · How to mount a speed light onto an ArcaSwiss plate?
Most cold shoe adapters don't have a method to keep the adapter oriented correctly after attaching directly to an Arca plate; Leofoto has the Leofoto FA-03 Flash Cold Shoe Conversion Adapter for ARCA Clamps which is designed for this purpose:
p.1 #6 · How to mount a speed light onto an ArcaSwiss plate?
Here's an assortment of various hotshoe adapters I have. Some are directly Arca mountable. Others have a 1/4-20 thread so you can attach a plate to then attach to a clamp.
You can read the models on those that have them. The Sunwayfoto and Leofoto feet in front are totally static and require the attached device to do the clamping. The one in back with the red knob is much older and has no brand name. That has its own clamp.
I suggest getting an assortment. They all have slightly different shapes and do not all fit all hotshoes. Some are too small, some are too large. For newer speedlights like Godox, I find the easiest solution is using the plastic mounts that come with the flash heads like the one on the left. The flash mounts securely in that because the locking pin from the shoe has a matching hole to extend into. Then the foot threads onto whatever 1/4-20 gadget you want to use.
p.1 #7 · How to mount a speed light onto an ArcaSwiss plate?
Hello and thank you for your post, I think the one suggested also above and on the right in your photo, the LA-03, would be the best fit, I thought I might use the little Godox IT30Pro as a backlight for some portrait and as such mount it onto either a tripod or a smaller light stand, have no clue how to mount on a light stand but the idea of an ArcaSwiss plate to mount the HotShoe contact on seems very practical, issue being I still can't find hot to get an LA-03 here in Italy.
p.1 #8 · How to mount a speed light onto an ArcaSwiss plate?
Depending on how you feel about ebay, there are several listings on the Italian ebay website for the Leofoto FA-03, but all of the listings on the Italian site source their products from the Leofoto USA site, so you might as well order directly from the USA site: there contact information is: