[H] Some questions for HIGH league ZERG from a newb please :)

  (Edited: )

Before I go on..

(I think this is the right section for this...) Let me say that I've looked around on the site (I know the dailies/newbie tuesdays) and on teamliquid and such, but most of the guides and things I find either don't answer my questions exactly, are pretty old and I don't know how well they apply anymore to the game currently, or are generalized to all races and do not focus on Zerg, which is the only thing I am looking for, not Terran or Protoss related things, purely Zerg. 

So, onward! (I will try to keep this organized as possible.)
As said in the title, I am looking for high level skilled Zerg players to help me out with my questions only. I'm looking to get a few pieces of advice from the players I wish to be like. It would mean so much if you could even answer a few of the questions you know, doesn't have to be everything, anything helps.

      *   My skill level (or lack thereof)

I am a pretty new player, a massively nooby one at that, it's almost an achievement. I haven't played any ranked matches yet so am not even bronze, I've played pretty much just against AI's and against friends in broodwar some in the past, not tons though. I could pretty much be treated like someone who's never seen the game when it comes to competitive play and general skill :P I've watched more games than I have played and want to start playing more and getting better at Zerg.

      *  Introduction to my questions

There are so many builds, strategies and playstyles ect. I've read/watched for Zerg that I am pretty overwhealmed and don't know where to start with beginning to learn Zerg effectively. I feel there's so much to learn that I don't know where square 1 2 and 3 is. 
**ANY advice or good relevant guides for Zerg from high Zerg players for basics or anything at all in general for Zerg will be greatly appreciated.

\(^0^)/ ***QUESTIONS*** \(^0^)/ (in spoilers)

(May add more questions as I think of them)

Basics things to worry about?
What are the most important basic things to be worried about with Zerg? I know not missing larva injects is one thing I always hear is crucial, and not getting supply blocked are two things.

Beginner builds to practice?
For a new player who is still learning EVERYTHING pretty much, what is a build or a way to play or something you would suggest that I can start with to learn to get better, your suggestions/advice?

Where would you suggest I put everything on hotkeys 1-0? Where do pro Zergs hotkey everything? 

Army Hotkeys?
I've seen many who put their whole army on 1. But my thought is what if you have your whole army on 1, you have to pull them to one of your bases to defend or something, and then the rest of your bases are defenseless? Or you pull them all to go attack and home is defenseless.

Larva inject effectively?
What is the best way to do larva injects? In pro matches I will see Zerg players screen flick so fast to each hatch and inject, and instantly flick to the next hatch and inject. How do they do this, is it how their hotkeys are set up or something?

Why ling speed?
Why is zergling speed seen as so important? Given zerglings are weak compared to the other units, why is it not better to spend the gas/mins on something else?

What exactly IS macro?
I hear it tons, pretty sure I know what it is. But I would like a recap just to be sure lol.