Totally new to crafting

[Caimie_Tsukino]

Actually, my old original crafting guide still applies to any new crafter these days:
http://ffxivrealm.com/guides/ff14-ad...ie-tsukino.39/

Your question 3 was answered by "Ch1: A Reason to Craft"
Your question 1 was answered by "Ch2: Picking a Few Main Crafting Classes for your DoW/DoM", "Ch3: The Benefits of Leveling All Crafting Classes to Level 15 for Cross Class Skills", "Ch4: The Importance of WVR & BSM to Crafting", and "Ch5: The Importance of CUL & food". Chapter 3 has also given you a sequence of which class(es) to level up first for cross class skills.
Your question 2 was answered by "Ch13: Leveling Crafting Classes"

Carpenter lets you HQ easier with Byregot's Blessing crossclass skill at Level 50.

In my opinion, although it is true that Byregot (CRP 50) is a very desirable skill, there are other priorities that can help one to push a class towards lvl 50, and that's obviously all the level 15 cross class skills.

Do you want to make glamour gear? Then culinarian is the worst first choice.

As to which class(es) to reach lvl 15 first, I actually recommend LTW, CUL and ALC. With these Waste Not, Hasty Touch and Trick of the Trade, it allows someone to HQ items very early... as early as lower than level 15. Thus, even though CUL appear useless if you're only interested in making furniture or glamor items, it's important to get Hasty Touch for the sake of leveling a class that will eventually be used to make furniture (even though we understand that furniture does not require the use of any "touch" at all).