First and foremost welcome here
I've actually been through the same cycle as you recently as i just bought my wife a BR03-92, only to realise that the rubber strap is too long for her. And i called up B&R boutique in Singapore and in KL to enquire. So here are my answers to your questions:
1) For original B&R rubber straps, yes there are only 3 sizes - extra short, standard and extra long.
2) You can only choose the size of strap if you purchase it from the boutique itself. If u purchase from AD or retailer, most likely they won't be able to let u choose your strap size. And that usually means the watch is most likely to be fitted with the standard sized strap.
3) If you want a replacement strap, there are plenty of aftermarket options. But to get a rubber strap that is short in length but 24mm in lug size is not easy. I'm also unable to find 3rd party rubber straps that is short in length but 24mm in lugs (BR01 & 03 are 24mm lugs). I think the logic is because given 24mm lugs, it means that the watch is not small. So likelihood of the wrist being a men's wrist is more than a lady's wrist. So standard size fits an average man's wrist.
I would suggest you can look around online and see if there are straps maker who customizes straps. But my findings are such straps maker that do customization are usually doing for leather only.
Well, that's all from me. Perhaps you can find something that i can't, let me know by then too. Enjoy your watch and wear it in good health.
