1) There are 10 Martial Arts right(the normal ones, not Ki stuff)? Could I buy all 10 at first level to get an extra 100 CM(Assuming they all give +10 CM each)?
Nope; there is a limit in how many Martial Arts you can master depending of your skills.
2) Theoretically assuming I can get 50 base CM for being a Technicist, 100 more from these Martial Arts styles and another 40 from the Martial Master Advantage, for a total of 190 CM at level 1...could I buy Ki Use(40 CM), Ki Control(30 CM) and then directly buy a level 3 tech(like Fifth Chain: Garuda for 90 CM) or are there limitations in place that keep you from purchasing a level 3 tech at first level even if you could pay for it CM-wise?
As i have told you, you can't get 100 CM using Martial Arts in early levels.
Or in short, are the levels on the key techs used for more than just indicating their general power level?
They only indicate its general power level, but you need first to have 1º and 2º levels ones in order to use 3º levels techs.
3) What's the difference between an (insert Warrior archetype of choice) that fights unarmed and a Tao?
Mnn... is quite complicate to explain it here... ^_^
Do Tao's get special benefits for fighting unarmed that no other archetype gets or what is it that supposedly makes them better at unarmed combat than everyone else?
Nope; all archetype can use all kind of skills, but in "game", is far better to do it with a Tao.