[CentOS] RAID 10 on Install?

Hi All,

How can I RAID 10 on install? (the names myRAID1 and myRAID2 are just  
for example purposes)

I select a custom layout....

/dev/sda, sdb, sdc, sdd are listed...

I create a partition of Software RAID on each of sda, sdb, sdc, sdd

Create a swap partition on sda?

Click RAID and take sda and sdc and RAID 1 to myRAID1

Click RAID and take sdb and sdd and RAID 1 to myRAID2

Click RAID and take myRAID1 and myRAID2 and RAID0 to MYRAID

This leads me down to swap. If I create swap on sda, then dont sdb,  
sdc, sdd then all have unused space of the size of swap on sda?

What is the rule of thumb for Swap these days. Back a long time ago it  
was double the RAM in the machine.....but that was a long time ago,  
what is best now?

Thanks for the chat!
-Jason