I have a Windows 8 Computer, two 32GB iPads and a 16 GB iPhone 5c. I have an iCloud account and have just purchased iMatch. Not sure how any of this works. Can I store my iBooks, and other apps in the cloud? Does this save space. Will all of my "stuff" sync among the devices? and how do I access things that are in the cloud?
iTunes Match is only for music : http://www.apple.com/itunes/itunes-match/
Using Match on an iOS device : iTunes Match on iPhone, iPad, or iPod touch
For your ibooks and apps, they will be available in the cloud for future redownloading, but only if you remain in the same country (you can't redownload items downloaded in a different country), and if they remain in the store - rights-holders occasionally remove their items from the store. You can't move ibooks or apps to the cloud, the rights-holder could remove them from the store at any time, in which case you won't be able to redownload them. Ideally you'd be taking a backup copy of all of your downloaded items via your computer's iTunes and not relying on being able to redownload them - you can copy downloads from a device to your computer's iTunes library by connecting it and using the File > Devices > Transfer Purchases menu option.
An app will need to be installed on your device for you to use the app on it. Similarly an ibook needs to be downloaded into the iBooks app on it for you to be able to read it.
Whilst the apps remain in the store you should be able to redownload them via the Purchased tab in the App Store app on an iOS device, and the Purchased link under Quick Links on the right-hand side of the iTunes store homepage on your computer's iTunes. iBooks (whilst still in the store) can also be redownloaded via Quick Links and the Purchased tab in the iBookstore in the iBooks app on a device.
If you use the same account in Settings > iCloud on your devices then you can keep things link contacts, calendars, Safari bookmarks in line between them (if you have those sections 'on' in Settings > iCloud on them).
What has to be done to download pictures and music to the cloud? And ten, how do you redownload it to your device?
If you've subscribed to iTunes Match, as you said in your first post, then you should be able to upload your music to it from the computer's iTunes that you subscribed to it from - did you have all of your music in that computer's iTunes library ? When you subscribed to it it should have scanned that library and uploaded its content to it. You can't upload music from an iOS device to Match, it can only be done from a computer's iTunes.
Subscribing to iTunes Match : iTunes Store: Subscribing to iTunes Match
Using iTunes Match on an iOS device : iTunes Match on iPhone, iPad, or iPod touch
For photos you ca use Photo Stream if you don't want to sync them from your computer, that should stream new photos between your devices - photos are only kept Photo Stream for 30 days, so if you want to keep them on any of your other devices then you will need to copy them from the Stream to a different album on that device.
Photo Stream FAQ : iCloud: My Photo Stream FAQ
How does iCloud work? Can I store my iBooks and other book filled apps? I just purchased IMatch. How does that work?
