Is the configuration OK for NAS + HTPC

Hi All

I am trying to build a nas + HTPC system for home purpose. This is my first post on this forum. Please do not be harsh if some of the questions are naive.

I have some experience building a simple destop pc at home and installing window sw. I do have some linux background and familiar with it.

If some of the questions are answered in other threads, please provide links to them.

Here is the summary of what I am planning to do:

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Purpose for NAS + HTPC
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* Store Photos/Videos
* Store Media( like movies, music etc )
* Would like to run services like couchpotato, sickbeard, etc for torrent downloads
* Abilitiy to have attached tv tuners to record shows on the nas.
* Connect to multiple devices, Smart TV, other Pc( windows ), Android Devices, XBox( for xbmc client )'
* Data Backup
* Media Streaming

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Current Hardware that I have some may be overkill, please suggest any alternatives)
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* Mother Board: Asus M4a77td Mother Board: http://www.asus.com/Motherboards/M4A77TD/
* CPU: AMD phenom II X2 555 blk; 3.2 GHz dual core 80w 7mb cache
* Case: Antec three hundred 430 with 6 3.5 drive bays and 430W power supply
* Currently have: Corsair RAM non-Ecc 16GB 1333
* WinTV-HVR(950q http://hauppauge.com/site/products/data_hvr950q.html) - usb tuner - I have 3 of them and want to enable recording tv shows.

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Plan to buy:
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* Plan to buy ECC Ram.. Is this needed?
http://www.newegg.com/Product/Product.aspx?Item=N82E16820148646 )
* HD: Need to buy: http://www.newegg.com/Product/Product.aspx?Item=N82E16822178392 plan to by 4 of them.

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Questions:
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* Is the above configuration ok? Do I need to buy anything else, like Raid Controller Card's etc?
* The current case does not have any hot-swappable drives. Is this needed? If yes, any recomendations of what to buy?
* Which NAS to software to use? FreeNas or Synology or other?
* I would like to have the data backed up/snapshoted from other home PC's, how to set this up?
* Which RAID to use, i am thinking of RAID 5. Is Software raid better or HW raid?
* What Video card to use for media streaming?
* If I use FreeNas, can I host VM's?

* Any useful pointers/ suggestions to help successfully build the system and any things that needed to be avioded.

Thanks in advance.
Rama