Kappy has provided a list of very informative of Apple documents. I'll try to provide some direct answers to your questions.
KiltedScot wrote:
1. I open an iTunes Match account;
2. I supload my library to it;
3. Some purchases were made from iTunes, which will not be uploaded / counted towards the 25,000 limit;
4. Others, from CDs etc., will be uploaded;
5. If any that I upload, no purchased from iTunes, appear in iTunes...will these be uploaded, or will Match simply refer to the iTunes library and play them from there?
6. Any new files I add, from iTines or from CDs, will automatically be uplaoded to Match;
Not every track in your iTunes library will be physically uploaded to the cloud. There are 3 main statuses a track can be, which you can see in the iCloud Status column in the iTunes browser: Purchased, Matched and Uploaded.
Purchased tracks are just that. Tracks that have been purchased from the iTunes Store. They do not count towards the 25k track limit. However not every track you bought from the store will have a status of Purchased if the original item you bought is no longer availble in the store for some reason. These tracks will be either Matched or Uploaded.
Matched tracks are, again, just that. They are tracks in your iTunes library that have been matched to the same tracks in the iTunes Store. These tracks do count against the 25k limit. Not all tracks that you think should match will though.
Uploaded tracks are tracks that are not bought from the store or can not be matched for whatever reason. These tracks will be literally uploaded to the cloud.
KiltedScot wrote:
6. Any new files I add, from iTines or from CDs, will automatically be uplaoded to Match;
Yes, they will be added to the cloud. Tracks bought from the store will be automatically added and will have a status of Purchased. Tracks ripped from CD will be scanned by iTunes and will be either Matched or Uploaded.
KiltedScot wrote:
7. If I decide to cancel Match, for whatever reason, will I loose any oof the files, or are they already on my hard-drive anyway?
As long as the files are on your computer HDD, no, you will lose nothing.
When you activate iTunes Match the default location of your iTunes library does not magically change to the cloud. It stays right where it is on your comptuer and the original files are not modified or moved in any way. If you do not delete them, that's where they will stay.
