cutting speed has nothing do to with # flutes, # of flutes affects the feed rate - feed based on chip load per tooth. cutting speed is a surface speed, ie fee per minute and is determine by dia and rpm's
re AL bits, they have a different helix - if you are maxing out industrial cutting ok but regular bits work fine and you do not need a set of AL tooling in the homeshop.
i prefer 4 flute for general work, its not so wump wump wump and produces a nicer finish. 2 flutes are for plunging or for slots and have their place. this is mostly based experience with hss ... i wouldn't think it would be any different with carbide, the principle is the same. btw, why the predisposition to carbide? what are you machining? there are lots of reasons why one might go carbide but as a self proclaimed newbie I'm wondering if weighed all the pros and cons? great for industry where time=$$$ but for the home shop its more expensive tooling, easier to break and most home shop equipment does come close to making use of its higher removal rate capabilities. just a thought.