The SX72 is the one designed for that Philips ballast, so they're guaranteed to work well together. As for burning position, lamps up to 55W can be burnt base up with slight loss of light output, but the ideal position for them is horizontal.
NEVER burn them cap down
For more info on the general principles of lamps of all types, including SOX, I can recommend the excellent
Lamptech site, run by James Hooker, who is a member here.
See
this page for an introduction to LPS lamps in general.