Hexapod battery selection

i am building a hexapod… i have to control 18 servo motors simultaniously… for that i am planning to buy an arduino mega 2560… will it work well?? can i send signal to all 18 servo motors simultaniously directly from this board…?? which battery should i use to power arduino mega 2560 for providing signal to all 18 servo motors directly form the board with out burning off the board???

You will need the arduino mega servo shield like this

Each servo will draw about 1 Amp of current, for 18 servo, you can get 3000 to 4000 mAH 20C 7.4V 2s1p LiPo battery, but you to drop the voltage to 6V to drive the Servo by using DC to DC converter or UBEC.

http://robokits.co.in/shop/index.php?main_page=product_info&cPath=13&products_id=225

is this one fine.. can i connect this directly to the arduino mega board?? will it burn the board??

That battery is a little high for the board. It won't burn the board, but the 5V regulator will get darn hot.

Also, the battery will burn the servos. If they are standard servos, they are generally rated for operation at 4.8-6.0V.