Start up disk is full, and need new storage and back up strategy

Question

I am maxed out on nothing my iMac and Mac book pro and recognise I need to introduce a new external hard drive into the equation.
I currently have an apple time capsule with 2gb drive, that backs up the 600g iMac and 250g mac book.
I would like to understand if I could point applications such as iTunes, iPhoto and iMovie towards an external drive ( as long as it is always connected to either the machine...or perhaps network so all machines have access to the external drive)....and hopefully I would also be able to access my iTunes library ( on the external drive) via an Apple TV...without any fuss.
I would also like to use my apple time capsule to back up from both the iMac and Mac book internal drives...as well as recognising the data on the external drives that points to the respective computers.....eg the iTunes library etc.
Is this at all possible???
If so, which external hard drive solutions should I use ( I have seen some mention synology...but looked at the website, and so many models and not sure what I would need)???
And how would I go about lifting and shifting data, redirecting applications to read and write to external drives, and getting time capsule to back up as above.....and possibly even have an additional back up strategy that allows me to take regular copies of all hard drives and keep content in an off site location for data security...possibly in a bootable format???
Welcome all help and advice please.

Answer 1

You should never, EVER let a conputer hard drive get completely full, EVER!
With Macs and OS X, you shouldn't let the hard drive get below 15 GBs or less of free data space.
If it does, it's time for some hard drive housecleaning.
Follow some of my tips for cleaning out, deleting and archiving data from your Mac's internal hard drive.
Have you emptied your iMac's Trash icon in the Dock?
If you use iPhoto, iPhoto has its own trash that needs to be emptied, also.
If you store images in other locations other than iPhoto, then you will have to weed through these to determine what to archive and what to delete.
If you use Apple Mail app, Apple Mail also has its own trash area that needs to be emptied, too!
Delete any old or no longer needed emails and/or archive to disc, flash drives or external hard drive, older emails you want to save.
Other things you can do to gain space.
Once you have around 15 GBs regained, do a search, download and install OmniDisk Sweeper.
This app will help you locate files that you can move/archive and/or delete from your system.
STAY AWAY FROM DELETING ANY FILES FROM OS X SYSTEM FOLDER!
Look through your Documents folder and delete any type of old useless type files like "Read Me" type files.
Again, archive to disc, flash drives, ext. hard drives or delete any old documents you no longer use or immediately need.
Look in your Applications folder, if you have applications you haven't used in a long time, if the app doesn't have a dedicated uninstaller, then you can simply drag it into the OS X Trash icon. IF the application has an uninstaller app, then use it to completely delete the app from your Mac.
Download an app called OnyX for your version of OS X.
When you install and launch it, let it do its initial automatic tests, then go to the cleaning and maintenance tabs and run the maintenance tabs that let OnyX clean out all web browser cache files, web browser histories, system cache files, delete old error log files.
Typically, iTunes and iPhoto libraries are the biggest users of HD space.
move these files/data off of your internal drive to the external hard drive and deleted off of the internal hard drive.
If you have any other large folders of personal data or projects, these should be archived or moved, also, to the optical discs, flash drives or external hard drive and then either archived to disc and/or deleted off your internal hard drive.
Good Luck!