Finding Five Numbers

1. When I sum five numbers in every possible pair combination, I get the values: 0,1,2,4,7,8,9,10,11,12.  What are the original 5 numbers?
2. When I sum five numbers in every possible group of 3, I get the values: 0,3,4,8,9,10,11,12,14,19.  What are the original 5 numbers?

Extensions:

3. Is it possible to find a set of 5 numbers in either case above which results in the sums 1-10?
4. If the above problem is not possible, what is the longest series of sequential sums you can find?  For example, problems 1 and 2 have six and five sequential sums, (7-12) and (8-12) respectively.

1. -3,3,4,5,7
2. -3, -1, 4, 7, 8
3. There is no way to make 10 in a row.  Joseph DeVincentis' summary:
   The sum of 1-10 is 55, so (using pairs) the sum of the five numbers would have to be 13.75. The largest and smallest pairs add to 1 and 10 so the middle number is 2.75. Then from the sums 2 and 9 we know the second smallest and second largest are -0.75 and 6.25. This makes the smallest and largest numbers 1.75 and 3.75, a contradiction since our "second smallest" and "second largest" are more extreme. And likewise our sums do not add up.
   Using triples, the sum of the five numbers is 55/6, so subtract each of the ten sums from this number to get -5/6, 1/6, 7/6, ... as the sums of the pairs. Now the same logic as above applies; shifting the set of sums by a fixed amount does not change the result; it only changes the numbers you calculate along the way to the contradiction by half that fixed amount.
4. For 9 in a row, there are many answers.  Jeremy Galvagni provided these.  The five numbers: {-1, 0, 1, 3, 6} can sum by twos to give -1, 0, 1, 2, 3, 4, 5, 6, 7, 9.  This is a sequence of 9 in a row (-1 through 7).  The same five sum by threes to 0, 2, 3, 4, 5, 6, 7, 8, 9, 10.  This is a sequence of 9 in a row (2 through 10).