Crafting/Gathering questionFollow

I am always a crafter and gatherer. In this game it appeared that you can only go into crafting at level 10 or thereabouts.

1.)Now that I am looking more into it I see that apparently you can become a gatherer already at level 1? is this right?
2.)Can you be a crafter say weaver at the same time as being a gatherer (say botanist)?
3.)I guess you can only be a crafter for one class?
4. Say I become a gatherer at level 1 and at level 10 want to be a Weaver, do I have to drop one (can I drop one) to start Weaver?

I understand that your 'normal' class, say such as archer, can branch out into other areas such as a swordfighter as well. Does it mean that I can branch out into something else at level 10 and can this ONLY be a crafting profession OR a different class profession?

This is all very incredibly complicated! For instance as a starter weaver it took me forever to work out what I am supposed to do to start doing weaving excercises, nothing at all tells you. you are told to make something. You browse around for a weaving table and there is none. I then worked out that a weaving gadget 'magically' (and illogically) suddenly appears in your hand.

Is there anywhere a worthwgile guide for this game, is it worth it to purchase one of those guide books like preema or killer guides?

1: You have to be level 10 before you get the ability to change classes at all, including to crafting/gathering classes
2: You can have all classes at the same time, but can only be using one of them at any given time. So you can level your Weaver class and Botanist class and Pugilist class and Blacksmith class, etc etc. All these levels are saved and you can switch classes at will (after level 10 and you get the ability to do this).
3: Level all the things
4: No. Level ALL the things.

I realize coming from another MMO, FFXIV's class system is kind of confusing and counter-intuitive. But trust me when I say that once you use it, it makes perfect sense.