Should I start/plant Leek seeds?

Should I start/plant onion seeds?

Should I leave small garlic cloves in the ground all year or two years until they are large enough to harvest OR should I pull them when the tops dry out and let them cure and THEN replant them Oct/Nov for my area until they attain a good mature size?

Also, same question about onions, I planted some red onions and have some other pre-package sweet and white onions I purchased in late spring, I figured it was too late to plant them so I have had them stored in the fridge until this fall.

However, I did go ahead and plant a few of the red type of sets, but they

1. Didn't get that large.

2. Didn't do that well.

3. HOW deep should Lincoln Leeks/onions in general/and garlic in general, be set in the ground?

What is the best food I can feed them to help them grow larger and WHEN should I apply it and WHEN should I re-apply it?

Are ground is good soil, but sort of sandy/loam with a hardpan about 1 ft down. I did add mulch to the area the onions original where growing in and the garlic I started too.

The garlic I started this year just turned into little bulbs that looked very much like a regular onions, should I/can I re-plant those in Oct/Nov. for actual cloves next year?

Sorry this is long, but I really need to know this, I have lots of seeds of different types and onions and 1 type of leek, along with regular garlic I believe is called silver skin and just received some elephant garlic as well and I do not want to mess up and lose any of them because of my lack of knowledge.

This was my first real attempt at planting onions and garlic.

Any help would be appreciated, thanks in advance.