Using the Town Hall statistics, you can see how much food your population is consuming (and producing) each year. As far as how much EACH person needs a year, you can divide Used over the last year by total population to get an estimate. It's not exact, because people are born / die during the year so the population number fluctuates, but I get just over 100 food per citizen using this method.
To access the Town Hall statistics, build a town hall, click on it, and select the Production tab.
The issue with stone seems to be a "non-problem". Your problem as you state it is that your stone is mined at one location and used all over.
Your desire is that the stone be moved "ahead of time", supposedly because then the construction would be that much faster. The thing is, this doesn't make your construction faster, it would simply hide the cost of moving the stone to when you're doing something else.
Whether you move the stone ahead of time, or move it when you need it, the manpower required for moving x amount of stone from A to B is the same. Ideally, all your townspeople are busy all the time, so the time they spend moving the stone to a supposed "staging area" is time they're not doing some other task.
Worse, if the trip from the quarry, to the staging area, to the construction site is longer than the trip from the quarry to construction site, you're wasting manpower.
What you want to do is, when you start construction, set the building as top priority (F2 - 6 ). This will tell all available laborers to drop what they are doing and move resources to the building. Once that's done, the builders will take over and finish the job. This way you get the building done as quickly as possible, with the least waste of manpower.
Best Answer
"Having Food" is not synonymous with "Being able to Eat food".
If you have plenty of surplus, and still people dying to starvation, the problem likely exists within your supply chain. In my experience, this usually means people are involved in pathing very long distances, such that they starve on their way home to eat.
Use the info panel to follow starving citizens. Where are they going? Where are they coming from? I've seen at more than one Let's Play where folks have mistakenly designated buildings far away, long before a sane path to reach them exists -- the end result was people walking towards the structure, giving up 75% of the way there when hunger kicked in, starting back, and dying before they reached their homes.