Concerning your question about bracelet length, Autavia and Carrera's beads of rice bracelets are precisely 7 and 11 links long from the factory, just as yours.

As you mention, those bracelets don't have any inserting pins, so they must be sized by bending open the fastening, intermediate "C" shaped links in the back of the bracelet. Once you deleted the required number of pieces, the C links can be bent back into their original shape, what is allowed without a problem by the soft kind of steel used. I know it from experience.

Required tools are a watchmaker's screwdriver of the proper size and modeler's pliers. However, caution must be exercised to keep the nice factory finish of the bracelet.

As Jeff Stein once remarked, if you don't have the heart and/or experience, this is probably a job better trusted to a good watchmaker. Good luck!