does this require special line set? is this ductless? what are the dimensions of the air handler? does the condenser sit on a pad?

Depending on the application of this system, it will require a different line set. The line sets that are needed for this product are available under "Accessories" on the product page here. This 2 Ton 20 SEER ACiQ Stealth Central Heat Pump Split System is not ductless. The Air handler dimensions are: Height 48-4/5" / Width 21" / Depth 19-3/5". Yes, the condenser will need to sit on a pad.

If you have any further questions, please call us and we will be happy to assist you.