PTO is paid time off. Your annual salary is what you earn assuming you work for the full year. If you use some of your PTO days (whether for sick, vacation or otherwise), you will not be docked any of your salary for those days off. Companies used to give separate vacation and sick days. If you happen to take more days off than your PTO days, you will lose some of your salary.
Some do but others decided it was easier to combine it in to one as PTO. Whether it is use it or lose it, gets paid out at one time, etc. is based on state law and employment policy.
"it wit is" stated "Salaried positions do not always include overtime pay (though the culture of a work environment may 'unspokenly' encourage one to put in the extra hours anyway)."
I am not sure what "extra hours" means. If you are salaried (meaning exempt per the DOL rules not company definition), you get paid for whatever you work. There is no such thing as extra hours or less hours.
If you are salaried (as in exempt per the DOL rules), you will not get time and a half if you work more than 40 hours per week but as long as you work 1 hour in a week and are willing and able to work the rest of the week, your company would be required to pay a full week's salary. If you are hourly (non-exempt - whether or not classified as salaried by your employer), you would be entitled to time and a half for any hour worked over 40 hours.