Hey man! hope you have fun in this journey, but If you want to go wizard, as all the above, I would greatly recommend Wiz1-Pyro3-Linker2-(and last 2 ranks you can choose whatever you really want depending your playstyle but many go thaumaturge 2). Try that wiz build to start with because its super easy and powerful at the moment. Once you get the Agny necklace, its amazing damage (even at late end game lv330).
Enjoy!

SP pot answers all your SP problem. You won’t have any SP problem at the first place (only archers with 0 cooldown skill do). And for mdef, you can have those from gear and Nuele card–hopefully you have read about card system. Only full support clerics go for Spr.