Can someone link me the correct extension cord to use with this, please?

PER THE INSTRUCTIONS, you can use a 16 gauge cord of the cord is up to 50', otherwise it should be 14 gauge for a longer cord. Additionally, you actually want two prongs rather than three. This is because the device is double insulated, essentially meaning it has an alternate safety mechanism and should not be used with a three pronged extension cord. You are looking for 16/2 on the label, or 14/2 if going with a cord longer than 50' (the first number like "16" is the gauge of the cord, the 2nd number "2" is the number of prongs). Everything I saw at Walmart was like 16/3 and such, so no good (3-prongs), but you can find 16/2 or 14/2 cords at Home Depot or Lowes (any hardware store I imagine).

What type of cord is needed for this blower?

A 14 gauge or 14/3 OUTDOOR extension cord up to 50 feet would be enough, if need longer ones, a heavy duty 12 gauge would be even better. Hope this helps.

Will it blow sand off the driveway?

It has more than enough power to blow sand off anything.

what country is this manufactured?

The box says China. I know that mostly everything is made in China these days. But the leaf blower works fantastic! I like it a lot. I live in an apartment & it makes patio clean up super easy.