Question: I have music contents for more than 500GB in external HDD. I need to access it from my android application, How can I do this.  

1.Can I connect the USB HDD directly to the tablet? and access? OR  

2.If I share the content in my local network, can I access it from Wifi like accessing shared folder in windows?  

OR any other suggestions plz..

Answer: 
You should be able to connect it directly to the tablet (with a USB OTG adapter if necessary). It should mount automatically under `/sdcard/usbStorage`.
If your tablet lacks a USB host port and OTG adapters won't work due to some tablet-specific limitation (I've had this happen), the free ES File Explorer app will allow you to [access network shares](http://www.techrepublic.com/blog/tablets/connect-android-to-windows-and-samba-shared-directories/1262).