Linux daily, weekly and monthly network usage

Check out the script AutoMySQLBackup https://sourceforge.net/projects/automysqlbackup/

This is a great script to backup one/all databases, using mysqldump (assuming these are mysql databases)

Those numbers seem sane, if (as people have commented) your numbers of users/talkers are relatively constant throughout the day -- or at least, average out at the figures you've started from. http://goo.gl/fdp3P certainly gives a similar final answer, just under 1 TB per month.

I think the useful way to look at it is actually in reverse: in a month, you can use 10TB of transfer before risking overage charges or bandwidth throttling. 10TB per month is around 32Mbps -- so how many users/talkers would you need to average at to reach this? At maximum quality, this allows you something like 4 talkers and 60 users (32Mbps/133.6kbps ~= 240) averaged through the month before you max out your bandwidth -- assuming you don't need the allowance for anything else, of course! Obviously if you're already using half your transfer allowance for something else, you need to halve this...

Sounds to me like you've got plenty of bandwidth available for the task, even if the (worst case) estimates of what you'll use are a little alarming at first.