1. Some recyclable products have a number within the recycle sign. What does those numbers mean? I think they go up to 6 or 7.

2. Also, which one of these are safe for storing food and not leech any of the plastics' chemical into the food or water?

3. Another thing, which ones are safe for the microwave?

The vast majority of the plastic/recyclable products don't bother labeling what they are or can(not) do. They just slap a number on it.

I hate to post just a link but this link Resin Identification Codes - Plastic Recycling Codes (http://americanplasticscouncil.org/s_apc/sec.asp?TRACKID=&CID=313&DID=931) should just about answer all of you questions. (O:

1. Some recyclable products have a number within the recycle sign. What does those numbers mean? I think they go up to 6 or 7.

2. Also, which one of these are safe for storing food and not leech any of the plastics' chemical into the food or water?

3. Another thing, which ones are safe for the microwave?

The vast majority of the plastic/recyclable products don't bother labeling what they are or can(not) do. They just slap a number on it.
The numeric codes that you see on many plastic items are used to help sort post-consumer plastics for recycling purposes. Different types of plastics are sometimes referred to as “resins” and the numeric symbols are known as “Resin ID Codes.” Each number (1 through 6) signifies a specific type of plastic and usually appears inside a small triangle (often formed by three adjoining arrows) imprinted on the bottom of a plastic item. The number “7” is used to represent a group of other plastics or combinations of plastics. Resin ID codes are not intended to provide guidance on the safe or appropriate use of any plastic item and should not be used for this purpose.

Use only number 2-4-5 throw all others away.
As for using them for reheating food I would not do that.

Kim, always check the date stamp, this post was in 2006. http://healthychild.org/5steps/5_steps_5/