Are the point costs inclusive for each step, so a four step fighting style costs 4 points, or are they additive, so a four step fighting style costs 10 points?

From the look of it, I would go with whatever the ST of the game said.  It is a touchy subject even on the White Wolf forums.

Every where I've played is that 2 dots gets you both the first and the second abilities.

Same here.

Yep!

From what I understand, you HAVE to buy as much as you can.

Striking Looks 2 = 4 xp. You can't buy the "one dot" striking look so you don't have the cumulative effect. You have to buy the whole two dots at the same time.

Striking Looks 4 = 12 xp. First you by the 2-dot striking looks, then you go to the next step which is the 4 dot striking looks. You pay for each step you can.

Fighting Style 2 = 6 xp, 2 for the first, 4 for the second. You first buy FS: 1, then you buy FS: 2, and so on and so forth.

If a merit has a solid block cost, like Inspiring (****) then you must buy all four dots at new dots x2, therefore using the example Inspiring costs 2/4/6/8/ = 20.

If the merit has an either or cost, then you must buy one block or the other at new dots x2, therefore if purchasing striking looks (** to ****) one must buy 2/4/ = 6 or 2/4/6/8/= 20.

A graduated merit like most Fighting Style merits or more succinctly Resources (* to *****) may be bought at any level between the first or the max, dependent on the XP available, at new dots x2. Therefore Resources * is 2, and resources ***** is 10, however each level must be bought individually just like any other merit, therefore the merit still conforms to the 2/4/6/8/10/ structure.

The reason for this is that it prevents sheet cheese because to buy Resources ** from no Resources at all would cost 6xp, and then to purchase Resources *** would cost an additional 6.

In the Camarilla, seeing as how this is functionally slower than molasses and hurts like an SOB, the structure was adjusted minorly:

Block merits cost X for the whole block where X is the number of dots. Therefore, Inspiring (****) costs 8xp in the camarilla, and Striking Looks (** or ****) costs 4 or 8. However, Graduated Merits like Resources and most fighting style merits were not changed because most of the graduated merits also have far reaching affects on Game.