Time Capsule is simply a back-up appliance.
You can most definitely access the hard disk of the Time Capsule in Finder, it will be on the left hand side of a new finder window. you will need the timecapsule username/password.
You can also attach a USB drive to the Time Capsule to share files.
Also if all apple computers are using 10.7 or 10.8 you have access to AirDrop where you can share files locally.
it really depends on your needs and current set-up.
DropBox is another possibility for sharing files and it is free for the first 2GB of storage.
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