No edibles can be planted in soil or within at least 5 feet of soil treated with Termidor or any insecticide that isnt specifically labeled for use on or in a vegetable garden. If you need to plant in an area termidor was used you would need to remove the treated soil and bring in fresh soil before planting.
Termidor SC (20 oz bottle makes 24 gallons of mix) is mixed at 0.8 fl oz per gallon of water and Dominion 2L (27.5 fl oz bottle makes 50 gallons of mix) is mixed at 0.6 fl oz per gallon of water.
Termidor SC is better than Talstar as it promotes a transfer kill eradicate the colony and will last for up to ten years in the soil. Please see our Termite Guide. The Square footage is not important in a trench treatment. Linear feet is most important. One 20oz bottle will cover 60 linear feet of trenching.
Termidor is designed to bind to the treated soil for longterm residual, so you would not have to worry about the application breaking down more quickly. The concern would be that your barrier is covered up with untreated organic material, thereby limiting insect control. We do suggest that mulch or similar groundcover be kept at least 12 inches from the foundation, so if this application is done accordingly, then your Termidor barrier would remain intact and effective.
We cannot answer that question for you. You are definitely not required, however, if your state requires a termite letter at the time of closing, only professional companies can issue these letters and if you do not have an active contract with a company you will usually be forced to pay a large sum to have your house treated to get a clearance letter. You should call your state Department of Agriculture which is usually the department that manages pest control companies and ask if your state is one that requires a termite closing letter when selling a house.
You definitely do not have to treat all at once. A Termidor treatment can be spread out over a few weekends or whatever time frame you want to. Please read our "How To Do A Termite Treatment" article if you have not already. You are also welcome to call us with any specific treatment questions. We are here to help.