Ability scores and bonus spells

[Amaril Amakiir]

This link is a table of additional spells per day, for various ability scores. (http://imgur.com/R4Ez6Xi)If say, a 4th level wizard had 18 intelligence, would he get an additional 3rd and 4th level spell, even though he is of too low level to cast them?

If not, does that mean higher intelligence simply boosts the save DC of his spells (in addition to out-of-combat bonuses)?

[bbkilla]

from SRD
"The ability that governs bonus spells depends on what type of spellcaster your character is: Intelligence for wizards; Wisdom for clerics, druids, paladins, and rangers; or Charisma for sorcerers and bards. In addition to having a high ability score, a spellcaster must be of high enough class level to be able to cast spells of a given spell level. "

and yes, it means higher DC

[nyjastul69]

bbkilla is correct. Also note that there is a stickied Q&A thread for these type of rules questions.