Ooooooohhhh, lotta questions! First off, welcome to the swarm!
I suspect I know there build your talking about, but I can’t say much about it without knowing more details. Some builds are designed to bank resources for a bit then explode into tech and upgrades with some units. I’m guessing your particular build is designed for an early push, so there are 2 good options for those resources.
1- make more units like zerglings to reinforce the roach ravager force. Zerglings are the fastest unit in the game with their speed upgrade, so they reinforce quickly.
2- make more drones and another hatchery, preferably as an expo. This will make for a very smooth economic transition into the mid and late game.
Gases - you ideally want to take most or all available gases once you start advancing to lair tech. That when Zerg starts using most of its gas. Hive gets even more gas heavy, so don’t be too slow on expanding, roughly every 3-4 minutes.
Queens you generally want 3 or 4 by 4:30. A rule of thumb is to have 2 Queens for each base up to 8. Some are for injects (yes they do stack), some for creep, a couple to stack energy for injects. Arguably the best unit in the game as the only tanky spellcaster w/ healing. These will be your core defense for the early game.
Anti air is situational. If the opponents army is predominantly air units, you will want a spire. Hydras can handle supporting air, but a fleet will generally overpower hydras as they aren’t very tanky. They are better for general pushes tho since they attack air and ground from a reasonable distance for good damage, so they are a good beginners unit.
Number of units to make? Usually timing is more important than the exact number of units. Obviously more is better, but upgrades make a huge difference in this game, so any given timing will consist of starting by making the required economy, tech (including upgrades needed), and then non stop units until upgrades finish. In a nutshell, it depends. Defending is similar, keep an eye out for your opponents army and make units accordingly.
Swarm hosts are situational. They are very good at surgical strikes into defensible areas, locusts fly in and tear down tech or bases very quickly, but have a long cooldown. The hosts are dead weight until the next wave, so be careful to not get them killed. Lurkers are an excellent support unit but can be a bit vulnerable when attacked directly. They are best when forcing an engagement in small areas or chokes as a support damage dealer. Good control is a must but not overly difficult, so add them in as you feel comfortable using them.
Vipers are good with anything really, but best with a pack of hydras or corruptors. The spells synergize well with damage dealing units by negating damage or singling out units.