Selective use of iCloud with multiple laptops, multiple iPods and iOS devices?

Question

I haven't brought my MBP13 to Lion yet.  I do have an MBA that runs Lion.   I have hesitated to take the MBP to Lion and set up iCloud because I just don't understand what the options are for selective "sync" of various sorts of data among one or more Macs, their iPods and iOS devices.   The material I can find so far does not in any way make it clear to me in advance what sort of selectivity will be offered if I turn on iCloud.
Aside from that my DSL connection does not offer a stellar download rate, and I live in a dead zone for cellular signals,  so I do not operate in an "always on" state.   I turn on my laptop's WiFi or plug in an ethernet cable a few times a day and similarly might turn on a mobile device a few times.   Past that, I'm offline.  I've lived like that with my Apple gear for 30 years and that's just how it is for people in rural areas of the USA.
All or most of my so-called "syncs" are the manual sort.  I pick out what info I want on any device and drag it there after connecting the devices.  If something I want on a mobile device can't be dragged there, or the alternative dread "sync" doesn't offer enough selectivity, I just settle for not having whatever that item is on whatever that device is, assuming I can't figure out a way to hammer the system into letting me get it on there (like temporarily adding movies to my main library from a separate library and external drive,  then drag to the iPad, then eject the iPad and delete the movie listings from the main library to reduce the clutter again).
So.    I don't  keep ALL of my various types of data (mail, music, movies, notes, PDF files, app data) on ANY of my devices.  I couldn't make them fit,  and I wouldn't want them all on everything anyway.    I don't always even keep any mail setups on a particular mobile device.  I might have one there for a particular time frame, say over a weekend,  and then disable or delete it.   That works fine for me.  I shudder to think what would happen if I had an iCloud setup and did that.  I have visions of my entire mail setup on one of my laptops being deleted if I delete it from an iOS device...
Beyond unwanted deletion?   Unwanted addition!   The last thing on earth I would ever want to do is set up iCloud and then find out that it wants to stash hundreds of GB of movies, hundreds of PDFs, thousands of music tracks, etc., on, say, my original iPhone that I still use as a WiFi device and occasionally add a few tracks of music to, or change up its playlists.  Not to mention what would happen if it tried to stash all my stuff on some unsuspecting little iPod touch used just for audiobooks.
I am afraid that iCloud will work like the dread "transfer purchases" thing works now.  The "transfer purchases" doesn't let me say WHAT purchases to transfer.   There's no way I want a movie I have managed to take from a secondary iTunes library onto an iPad transferred "back" to my iPhone or my MBA or to ANYTHING just because I turn some device I own in order to check the weather.   Maybe I never purchased that movie on the iPad.  Just because it's not on the main library any more doesn't mean I want it to be there, either.
So how can find out ahead of time how iCloud is going to work for someone with lots of different types of data on several laptops where all the so-called "syncs" at present are as manual as I have been able to make them?   
Or can someone just tell me hey you know what,  iCloud is not designed for you,  just don't go there.   
Either way I'll be grateful for some help here.  Sure I can clone my laptops and then back up all the iOS devices and copy those backups to externals, and then turn on iCloud and hammer on my stuff for two days to see what happens.  But why should i do that if someone can say up front that iCloud is or is not set up for highly selective sync options?

Answer 1

iCloud does not sync movies or general files, so that problem doesn't arise.
iCloud will:
Sync Calendars
SyncSafari  Bookmarks (though not display them on the iCloud website)
Sync Contacts
Sync photos added to or taken on one device onto other devices
Access @me.com email
Sync iWork documents only between your Mac and iOS5 devices - automatically from iOS devices by by dragging individual documents from a Mac to the iCloud website (and the cannot be re-downloaded until they have been edited on an iOS device)
Each of these can be turned on or off on each device; you cannot selectively sync within one data type - i.e. it's all or no Contacts, not a selection, and so on.