You can book a taxi via following methods:
Online: http://www.helensburghtaxi.co.uk/
Telephone: +44 138 984 1642, +44 800 138 9234
Telephone: +44 783 159 1173
Yes, it's possible to pre-book a taxi with Mikes Taxis, please contact the company.
Mikes Taxis has both regular and air-conditioned taxis, please mention your preference at the time of booking.
Please contact the company on their helpline number to make any changes.
Generally drivers will meet the passengers at the arrivals on airport pick ups but do check with the company.