Access windows shared folder via bluetooth
I know this is an old as hell question, but I thought I would answer anyway.

Simply put, this is impossible with the way you'd want to implement it.  Windows folder shares are SMB/CIFS, which is a NetBIOS/TCP/IP protocol.  Bluetooth is, well, the Bluetooth protocol.

Technically speaking, you could use Internet Connection Sharing (ICS) on your Windows machine and connect to the broadcasting WiFi.  You'd then be on your internal network, and you could access the share.  But that would involve using your device's WiFi, not your Bluetooth connection.