Buying a lesser maximize rod at level 7...or any level, really, is flipping stupid. It costs WAAAAAAAY too much!
Spending magical lineage and/or Wayang Spell...whatever traits on fireball is also stupid. I love it, it's iconic. But it's a HORRIBLE spell.
If you *were* going to go this route, for gods' sakes, at least combine Persistent and Dazing Spell instead of Empower and Maximize. Same spell level adjustment. Everyone has to beat 2 reflex saves or instantly lose be dazed for 3 rounds. Of course, I'd use dazing and persistent on a dozen other spells before fireball...
EDIT: 7th level wealth is 23,500 gp. Lesser Maximize rod is 14,000 gp, which is actually lower than I thought it'd be, but still over half your wealth and questionable if you'd be able to obtain so early.