1. The per diem amount is for overnight travel. If you leave at noon you only were gone for 12 hours so thats half the per diem amount. A run where you have to go to bed in the motel would be overnight travel. A run where you go out 300 miles and return 300 miles would not be elgible for overnight travel.
2. Its $52 unless you leave the country or go to certain cities.
3. I deduct the entire amount. I don't know what the IRS says about it, but I believe everything I do on the phone is business related. Even talking to the wife. She pays the bills and manages the household. This is just my personal opinion and I have heard this from a Tax professional on the trucking shows too named Kevin Rutherford. If you are real concerned then only deduct the business use percentage of your phone use.