S@squ@tch, I've done a bit more research, and while I still think the rule reads as if you need nonspellcasting class levels to 'overcome' with the feat, WOTC seems to disagree. One of their fastplays for the Xen'Drik Expeditions campaign has two uses of the feat in an ultimate magus build. So, based on that, your planned progression and the impact seem to work.
The WOTC FAQ clearly says that the bonus from Practiced Spellcaster is applied as best benefits the player, so yes, you would apply the feat first, and then the bonus from Arcane Power, giving him a CL 7 for sorcerer spells. Yikes.
The WOTC FAQ clearly says that the bonus from Practiced Spellcaster is applied as best benefits the player, so yes, you would apply the feat first, and then the bonus from Arcane Power, giving him a CL 7 for sorcerer spells. Yikes.