How would you feel about using necropolitan for your immunities?
Unless you get perform as a class skill, you'll have to be level 9 to qualify for spelldancer. Feat rogue may be a good way to get perform.
I'm pretty sure you can use the wizard variant that gives fighter feats and still use the variant that gives a domain granted power. So, you can get a fighter bonus feat at 1st level, then extend spell from the planning domain at 5th level.