iMac cleanup: can I delete these files? Using Omni Disk Sweeper, I have listed the very heavy files in my computer in order to, if possible, delete them and free up some space.

Of course, I am not going to risk tampering with my system folder, but there are some pretty big files about which I would like to know whether or not it is safe to delete them. Let me know if you know what these files are, and whether it's safe or not to delete them:

Private -> var -> vm -> sleepimage (6Gb) and swapfile0 (1Gb)

Private -> var -> folders (1Gb)

Private -> var -> db (1.4Gb)

Library -> Printers (1.6Gb): (I believe I can re-download the needed drivers if I ever purchase a printer from the System Preferences?)

Library -> Application Support -> iDVD (140mb) and iPhoto (591mb), not so large but I am not a user of these apps

Users -> Shared -> Adobe - 200Mb (is this even accessible by the main user's system?)

Users -> Shared -> Library -> Application Support (is this in use?)

Users -> Fabrice -> Music -> iTunes -> iTunes Media -> Mobile Applications - 25Gb - (I believe if an app was backed up from my iPhone there, it's either currently in my phone, or not supported anymore, or I can get it from the store again if I've already paid for it?)

Users -> Fabrice -> Library -> Mobile Documents (400 Mb)

Users -> Fabrice -> Library -> Caches (600 Mb)

Users -> Fabrice -> Library -> iTunes (900 Mb)

Users -> Fabrice -> Library -> Developer -> Shared (2 Gb)

Library -> Application Support: how can I find easily which applications are not installed on my system anymore?

In total, more than 50 Gb is used by very voluminous elements whose purpose I am unsure of. I wouldn't ask such a question if I hadn't been using Mac computers for the past 20 years and been able to explore and modify System files for many years; I believe modifying the System files can lead to problems... However some of these files look like they can be rebuilt by the system whenever needed, or are backups files/folders that one can easily part with without any consequences.

Thanks for any help!
Looking just at the big parts


You shouldn't touch anything in /private, as these are files used by OSX.
Removing unneeded drivers from /Library/Printers shouldn't pose a problem (I only have the Canon drivers for the model I'm actually using in there)
.../iTunes/iTunes Media/Mobile Applications contains all the apps you've ever purchased. You can, if you want to, delete those which you are not using anymore (and reload them again if necessary), but anything installed in your phone will most probably get resynced on the next sync
In .../Library/iTunes there might be some old iPhone updates left in iPhone Software Update which can be removed without problems
.../Library/Developer/Shared contains the Xcode and Development documentation, which can be managed via Xcode directly (or you just remove it and use the web-based version)


I wouldn't bother with the smaller stuff (including iDVD and iPhoto).