Garlic - how much to plant?

So, I had an epic fail with my peppers, tomatoes, etc this spring.  Pretty sure it was insufficient attention, and not transplanting at the right times.

Anyway, I LOVE garlic.  No worry about vampires at my house.  Since it's fall, and I'm let to understand that now, roughly, is the time to plant garlic, I'd like to do so.  I have a raised bed that was going to be used for strawberries, but we never planted it.  It's a bit weedy now, but I can probably pull the weeds and then use it for garlic.  The bed is made from cottonwood rounds for the walls, and inside is a bunch of mostly cottonwood slash covered by a mix of potting soil my wife mixed from peat moss, vermiculite, pearlite and probably some native soil.  First off, is that a good environment to grow garlic?  It's pretty well exposed to sunlight.  

About how much garlic should I plant (I know this depends on variety, but rough ideas are sufficient)?  We do cook with it pretty frequently.  Garlic and onions are the starting ingredients for probably 1/3 of what we eat.

Speaking of onions, are they a fall plant or a spring plant?  Is it desirable to grow them in the same bed as garlic or are they best kept separate?

Edit to add: What are some other good veggies to plant now, whether to harvest later this fall or next year?  I'm in the northern Puget Sound.

Garlic will grow pretty much anywhere that isn't waterlogged. It doesn't like wet feet AT ALL, but it's not too picky about soil. I've done garlic in the garden (intensive composting for 40 years), in straight sand, in pots, in sand mixed with potting soil, and it did great every time. The only time I had a failure was when i tried it in hydroponics. Great root system, no bulb.

It should be planted at least three weeks prior to the first frost, but again it's not picky. Two weeks, a month, whatever. As long as it has a good root system going into hard winter, it'll do great and you can harvest it in the spring.

Remember that depending on variety you'll get as much as ten times what you plant. If you plant five cloves, you'll get five bulbs, each with multiple cloves. You can also use the scapes in the spring if you have a hardneck variety.

If you eat one bulb a week, fifty is your minimum. If you eat two per week, 100. And so on, but remember to make allowances for replanting. I plant 125 cloves per year because we use it for medicine as well. Plant at least 3-4 inches apart, preferably six, and about 2-3 inches down.

Onions are a spring plant--if they go through winter they'll bolt in the spring and give you seeds, but that's probably not what you want. And it's probably a bad idea to plant them with garlic, since they would be competing for the same nutrients.

There are autumn onion types and they become ready before the spring planted ones. I put them near each other as they are in the same family so it makes rotation easier.

How many bulbs do you use? plant that in cloves plus 20% 10% for failure and 10% for replanting.

If you are wanting to plant perennial Egyptian walking onions this is a type that you would plant in the fall.  I just got my order a couple weeks ago and plan to plant them out soon.  I've gotta plant my garlic as well.

I just want to add, that if you like garlic and onions a lot, I imagine you like leeks also. There is an heirloom variety of leek called Scotland Leek which does best started in the fall and overwintered.

Green onions are another to enjoy and both regular and garlic chives. Beer battered fried chive flowers, need I say more? As for how much: I found that if you grow more of something you use more of it. Buy some different types, plant them, save your best, replant more than last year, keep doing that until you get sick of garlic...oh wait...not possible.  A good garlic year means garlicy bread sticks, roasted garlic, extra garlic in everything.  Garlic dips, dried garlic powder,  pickled garlic, etc. A bad garlic year you hope the other herbs do well to compensate. Onion is also pretty versatile. But onion you have to know when to hold and when to fold. A small bulb is better pulled early as a green onion than let dry. Onions grow bigger and better in drier fertile loose soil with plenty of sunlight,  but I get shallot sized ones  off some partly shady, hard, infertile soil. And no, you can't have too many onions either: French onion soup. Good luck!

I don't think you can ever have too much garlic. Well, I suppose you could but it would be hard. We're in the S. hemisphere so plant in March, harvest in Nov, and I have about 150 plants growing (also because I lose some at the last minute to mole rats) for a family of 5, and to keep enough cloves to plant. I have enough growing space over the winter, though I'm starting to want the space (and am starting to interplant so that when they come out in a month or so, the basil will be getting established.

Pictures of my spring garlic bed (new seedlings in foreground)