How to configure RAID 1 on Intel Rapid Storage, and partitioning design

Question

I would like guidance on setting up a RAID 1 system from BIOS with Intel Rapid Storage.

System details:

I have Click BIOS II running on a MSI motherboard (Z77A-G43). I also have 2 x 2TB hard drives.

What I've done so far:

From the BIOS, I have selected "RAID Mode" from Settings->Advanced->Integrated Peripherals->SATA Configuration->SATA Mode.

Now, when I reboot, I get an option to enter the "Intel Rapid Storage Technology" ROM. When I select "Create a RAID Volume", I'm given the option to choose the capacity.

Questions:

1. Is it possible to choose a lower capacity - eg 1TB - which would leave the rest of each disk outside of the RAID system?

2. Is this advisable?

3. If I already have data on one drive, would it be kept after this operation?

I plan to partition the disks to have a dual boot, for Windows and Linux, possibly with a separate partition for data. Its this data partition that I really need the RAID for.

1. Can I use LVM on top of RAID?
2. Is LVM for Linux only?

Any advice would be welcome.