does anyone know if this plant covers walls like rock soapwort does?
I don't know this particular variety, but this species and other Veronica and others will drape over walls like Saponaria although maybe not quite as abundantly.
Oh yes! they are growing abundantly, very nice little blue flowers and making a good "carpet"! Flowering is not very long but they are still nice with their evergreen leaves and not difficult at all, even in winter.
Good luck with them!