What are the restrictions on Wizard Bonus Feats?

From the SRD:

******************

At 5th, 10th, 15th, and 20th level, a wizard gains a bonus feat. At each such opportunity, she can choose a metamagic feat, an item creation feat, or Spell Mastery. The wizard must still meet all prerequisites for a bonus feat, including caster level minimums.

These bonus feats are in addition to the feat that a character of any class gets from advancing levels. The wizard is not limited to the categories of item creation feats, metamagic feats, or Spell Mastery when choosing these feats.

*****************

Is this a common sense restriction?  "take a feat that affects spellcasting?"

Wizard bonus feats must be item creation, metamagic, or spell mastery.  That's "the restriction on wizard bonus feats."

Non-bonus (regular) feats can be anything for which you meet the pre-req. You emphasized this point, but I'm not sure why.

Did I answer you question?

So the bolded statement applies only to the general feats availabel at every level?

That's correct.  The D&D books have a lot of bad technical writing.  The authors use way too many pronouns and they sometimes imply things that are untrue.

1) "...in addition to the feat that a character of any class gets from advancing levels." The word feat is singular, which implies that a character only gets 1 feat from advancing levels.

2) "These feats" at the end of the 2nd sentence is ambiguous (obviously).

3) Unambiguous, pronoun-free version:
Bonus feats are earned in addition to the feats (plural) that a character of any class earns from advancing levels, which are not limited to the categories of item creation, megamagic, or spell mastery.

*stabs the SRD in the face*