Can a Ranger in medium or light armor fight as if she had the Ambidexterity and Two Weapon Fighting feats?
You seem to have some confusion to the point of not having read the 3.5e player's handbook?
The 3.5e ranger class can select a combat style at second level. One of those two styles gets you the equivalent of the two-weapon fighting feat for free without having to meet prereqs. There is no Ambidexterity feat in 3.5e.
So yes, at second level, IF you select the two-weapon combat fighting style instead of archery, with the caveat that there is no Ambidexterity.
The short answer as I recall: Yes
Long answer: As long as said ranger has the class feature or two weapon feat. I also seem to recall that in 3.5 Ambidexterity was removed as a feat and was just included in TWF.