Your option 3 is the tricky part, you wont find a router with a built in HDD. You can get a router with external USB ports for connecting devices like hard drives but your always best to use a NAS device for network storgae. NAS will offer you much better perfomance than a USB device.
What VOIP functions do you need? Phone ports? Voip routers tend to be quite basic, you could get something like this and run it as a VOIP access point from a more powerful router...
http://www.ebuyer.com/product/107215...edium=products
Bittorrent client, I believe the Asus 700 had a bittorrent client was a failure as it still relied on external storage. On the toher hand there are a afew NAS devices now that support Bittorrent mode, one being the Netgear ReadyNAS...
http://www.scan.co.uk/Product.aspx?WebProductId=797762
To be honest that doesnt sound like a perfect router you have listed, it does on the other hand sound like something that will cook eggs it would be that hot!