Backup exec - mediasets - operation logic

Hi guys,

We’ve reciently bought a Tape library with 23 slots. We also have bought Backup exec but we have not experience working with it.

Now, we are worried and have some questions when configuring the backups.
In backup exec 2012 is available basically these possibilities:

-      Create partitions.
-      Create Mediasets
-      Configure overwrite and appendable options.

I would like some expert give us some advice about how is the best way to configure the backps and work with mediasets and media rotation policies

For example, If we have Daily, weekly and monthly backup, how should we configure and use partitions, mediasets and overwrite/appendable parameters in order to onfigure daily, weekly and monthly backups? Please, take in account account we have 23 slots.

For example:

Do you think it would be a good idea to set one only mediaset called “Weeky” for 4 weeks containing 4 tapes or it would be necessary to create 4 differents mediasets –one for each week- ?  

If we had one mediaset for 4 tapes, how  does Backup exec Know  how to choose one of those tapes depending on week we are? For example:

We have one mediaset named “Weekly”. Associated with this mediaset for tapes, labeled respectively:
Week1
Week2
Week3
Week4
If it is the second week, week2, how does backup exec know how to select the tape labeled week2 instead of someone else, week3 for example?
Please, give me an advice.

Thanks in advance