Are there specific rules on...

[Ixahinon]

Spell creations? Like how long it would take to create a 3rd level spell, etc? Or is that all basically up to the DMs descression?

[Nightson]

3.5 DMG pg. 35

[Sinfire Titan]

3.5 DMG pg. 35

See also XPH pg 95. I feel that method is more complete and balanced than the DMG method.

[Ixahinon]

Read the part in the DMG..that's all wel land good...but is there a timeline on the creation of the spell that the PC must follow? 1 Day/Spell Level? XP cost? Materials needed?

[Sinfire Titan]

Read the part in the DMG..that's all wel land good...but is there a timeline on the creation of the spell that the PC must follow? 1 Day/Spell Level? XP cost? Materials needed?

I believe it is explained in the XPH version I mentioned. They list it as one week per level of the spell, IIRC.