Hiya,
- Is every revision saved? Meaning: if I change a slash into a
backslash in a text of 12 kB is the space needed changing to 24 KB? And if I change a "then" to a "than" ist it changing to 36 kB than?
Yes, every revision is saved. And yes, this means that the database can grow quite big quite quickly, but you can set $wgCompressRevisions to true in your LocalSettings.php to combat this[1]
1. http://www.mediawiki.org/wiki/Manual:$wgCompressRevisions
- If I delete an article as an administrator, is it really wiped off the disk?
No. It'll just be marked as deleted, meaning (among other things) it'll not be accessible to non-admins anymore.