LTC 3305 usage

Hi,

  I am having a battery balancing requirement for 18 batteries.  My total output voltage of batteries is 192V to 260V.  I am planning to use 7Ah batteries.

1. I am planning to use maximum 7Ah batteries.

2. Can I get some lower-cost MOSFETs since current will be less.

3. I need to use 5 auxiliary batteries which will increase the cost. So which supercapacitor or high voltage capacitor can be used.