Time Machine

Time Machine does not overwrite old backups. It archives former and current backups. You cannot delete prior backups to save space. If that's what you prefer then use the backup drive with a different backup utility such as:

Backup Software

Using Time Machine is very easy, and all the tools you need come with OS X. If you later need help with Time Machine then I highly recommend a visit to Pondini's Time Machine FAQ for help with Time Machine. This is an extensive site with most everything you may need for using Time Machine. You will not find a better resource for Time Machine of OS X in one location. Due to the passing of James Pondini the site is no longer being updated. Therefore, some of the information may be outdated.

As an alternative, you can use any third-party backup utility your prefer. They all create straight file backups meaning you can restore individual files manually if you want by drag and drop copy.

Recommended Backup Software

1. Carbon Copy Cloner
2. Get Backup
3. Deja Vu
4. SuperDuper!

Visit The XLab FAQs and read the FAQ on backup and restore. Also, read How to Back Up and Restore Your Files.

1. Yes.
2. Yes, but older files are maintained for a period of time to allow recovery of older versions.
3. Time Machine takes care of this behind the scenes.

If you plan to remain with Time Machine, then you will need a backup drive that is at least 3 times the capacity of the Source drive.