Four kinds of problem in rotation down the page: adding and subtracting signed numbers (6 + (-11), -9 - (-19)), multiplying and dividing them (-11 × (-6), 144 ÷ (-12)), comparing two integers, and absolute value. Every problem is written on one line, because that is how integer arithmetic is written - the sign belongs to the number, and a column has no place to put one.
Answers can be negative, and often are. That is the whole point of the topic and the thing that makes it different from every other sheet on this site. Largest number sets the magnitudes the problems are built from; the sign rules are the same at 10 as at 50, so raise it once the rules are secure rather than to make them harder.
A whole number, positive or negative, including zero. -7, 0 and 12 are integers; 2.5 and 3/4 are not. These sheets stay inside that - there are no fractions or decimals on them.
Because -5 - -3 is genuinely hard to read, and two signs in a row is the thing students are being taught not to write. A negative number after an operator is always bracketed here; a negative at the start of a problem is written plainly.
Sixth and seventh grade. Sixth grade introduces negative numbers, ordering them and absolute value; seventh grade does the arithmetic - adding, subtracting, multiplying and dividing them.
Yes. Set Questions to Adding & Subtracting, Multiplying & Dividing, Comparing or Absolute Value, or use one of the pages linked below, which open with that choice already made.