"I eat and drink as I want" is correct too? (just "as", with an idea of "how", instead of "how much")
No, in this case it would not be correct, the Greek sentence is about quantity. But you are right, according to context όσο can take on various meanings—just take a look at this link (but don't blame me afterwards :-D ):
"I eat and drink as I wish" is proper English, but does not differentiate between quantity or quality of what is eaten.
I don't know if that was ever an alternative translation, but it's not anymore. ^.^
As I please would translate better to όπως θέλω, meaning however/the way I like. I don't think these have the exact same meaning.
I thought τοσο........οσο was as........as (τοσο κόκκινο οσο μια τομάτα) so why not τοσο πολύ οσο as much as?
Because it doesn't work this way in Greek :P It's not a word-for-word translation, and τόσο πολύ... όσο doesn't make much grammatical, or any kind of sense, for that matter. Τόσο πολύ all by itself translates to so/that much, and when it's followed bys something, it's usually followed by που. For example, Έφαγα τόσο πολύ που δεν μπορούσα να κουνηθώ (Ι ate so much that I couldn't move).