I have been playing StarCraft since the release of StarCraft 1.
First off I will recommend that you play both campaigns, WOL and HOTS.
After the release of HOTS, Blizzard implementad training missions and minor missions to learn about the mechanics of the game - you should do these.
But Zerg is often a balance between making drones and making units.
As you are new to the game. I would make simple builds. Instead of trying out complicated builds from the internet, start out by doing a 1 base build. This means that you focus on your main base, and build structures from there.
When you get the hang of this, try out some basic build orders from the internet, like a Roach Timing or Baneling busts.
So which units is easy to play and are good against all.
In general, building Roaches is fairly safe against all races. Roach and Zerglings do pretty good at the beggining of the game.
You can then, later into the game "refered to as mid-game", try to build mutalisks.
Reagarding queens. The point of the queen is to defend against rushes, upholding larve injects and spreading creep.
Creep is important as your units move faster on creep and grants you vision.
You should have atleast 1 pr. hatch, and 2 in the field spreading creep.
Also, make it a habbit to place one Spore Crawler in the middle of your mineral line of all your bases. It procets your from flying harrasment and can detect Widow Mines and cloaked units.
BUT, I will always recommend that you should get used to going for a "15 Hatch". 15 is the number of units you have, and Hatch is the Hatchery. 15 Hatch is you expanding at 15 drones.
And remember always to upgrade your units!
Get used to use a "rotation".
- Check inactive drones
- Inject larve
- Make Overlords
- Make Units (workers and regular units)
- Upgrade units
- Spread creep
I can recommend that you watch Day9´s cast.
I found some for you to start out with:
You can find a lot more on his page on YouTube or via his own Day9 webpage.