Yes

Sort of.

The mileage from home to your first location (be it the agency office to get your instructions or a pickup site) and the mileage from your last location to home would be considered "commuting" mileage and isn't deductible.
Any mileage inbetween is "business" and deductible.

Get yourself a calender, or keep detailed records of the daily business mileage and general notes about where you went. Good documentation is key with this deduction.

Now the confusing point -- if you meet the qualifications for "Office In Home" for your business, you can claim ALL the mileage, even that I mentioned as "commuting." From the brief description you've given, it doesn't sound like a business that would need an office. Check with an accountant or check the IRS site ( www.irs.gov ) for Office in Home about that.

If you claim the standard deduction you can't deduct your vehicle expense. If you go the long route and itemize deductions and claim to be self employed, then you can claim the mileage to and from the jobsites.

For the self employed, the vehicle mileage wouldn't be included as as an itemized deduction. It's got nothing to do with taking the standard or itemized deduction.

It's properly listed on Schedule C as a business expense.

Yes but keep a record of how much is driven for personal use and how much for business use.