Question about assembling a home media center

Hello, gentlemen and ladies!

I decided to assemble a simple computer as a home media center. Accordingly, I consider potential platforms XBMC and MythTV.

Here is its configuration:
1. Motherboard ,
2. The processor
3. 2 strips of non-memory memory in gigu,
4. Cooler on the processor
5. Housing .
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In connection with the upcoming purchase, I have a few questions:
1. Will the computer in this configuration pull the FullHD video (BD-Rips are assumed) while simultaneously downloading torrents?
2. Do I need to buy something else that the computer is effectively cooled or one cooler per processor is enough?
3. What platform for the media center to choose?

Thank you very much for your attention and I will be grateful for the answers.