From the Sponsored Magic power description (YS183): "If you’re paying full price, you get four focus item slots with this ability. If you have either Evocation or Thaumaturgy, thus reducing the cost of Sponsored Magic, you only get two additional focus item slots. If you have both, reducing the cost more, you don’t get any additional focus item slots."
As to Refinement, access to this power is limited by your Template. Wizards can buy it many times, Sorcerors can but it once per skill (Evocation/Thaumaturgy). No other Template explicitly allows it, though Emissary and Changeling have fairly soft limits on powers, and there's always the option of creating a custom Template. The reason for this seems to be that Wizards are assumed to have access to some degree of mentoring, whereas most others don't. That said, if you had the right justification -- such as your Sorceror was being actively mentored by a powerful Wizard (or maybe even an Outsider) -- then your GM could certainly judge it reasonable to buy some Refinement.
