Drive Configuration For New Wse 2012 R2 Building

Hello, all.

I am looking for a hard drive configuration recommendation for a new server I plan to set up for my home office with WSE 2012 R2. I want active directory, so I don't want to use WHS 2011.

I purchased a Lenovo ThinkServer TS140 70A4 with a Xeon E3 1225V3 3.2 GHz processor and no drives installed. It supports RAID 0, 1, 5 and 10 and I will install 8Gb of RAM.  I believe that I can also ignore the RAID and install several stand alone drives if I choose to do so.

Here is how I plan to create the drives. C:\ - OS; D:\ - Data; E:\Client Backups; F:\Server Backup (c:\, d:\ and e:\).  The client backups could also go on drive D: in a folder rather than a separate drive.  I also plan to use Crashplan to backup my server data and will create a NAS from an older computer to backup the server separately on premises.

I have purchased two WD Red 1TB Drives and one WD Green 2 TB (for the server backup)

I plan to use the server for:

• centralized file storage for word processing documents, spreadsheets, pdfs, some pictures and videos. Right now, we don't stream any video or audio from the server. My data is under 300 GB and I don't forsee it growing at a significant rate in the near future. This is fifteen years of accumulated files.  A maximum of three people will simultaneously access the server.  Mostly it is one or two people at a time.
• Ocassional remote access to files, programs on the server and client computers.
• Daily Client computer back up (three desktops and one laptop)
• Daily backup of the server drives
• Running Quickbooks and Quicken using Amieco RemoteApp

1. How I should handle Drive C:\ and D:\.  Does the OS NEED to be on a separate physical drive from Drive D:\, or can I place them as separate partitions on the same physical drive without dramatically impacting performance?
2. Also, what impact will a RAID 1 or 5 configuration have on the question above?  What I am running is important for my business, but not mission critical.  I can stand to be down for a day to restore a backup if a drive failed, although if I can avoid it with RAID 1 or 5, I will do so. 
3. Is there any advantage to running WSE in Hyper V or will that unnecessarily complicate matters for my setup?

Thanks in advance for your suggestions.