it is called the sum just like in adding.
The sum of all the sides of a given shape is the perimeter of that shape.
The shape is called a decagon. If all the sides and angles are the same, it is called a regular decagon.
This shape is called an icosikaitera. All of the sides of the icosikaitera are all of the same equal length.
A shape that does not have equal sides is called an irregular shape.
A six sided shape is called a hexagon.If all the sides have the same length and all the internal angles are the same it is a Regular hexagon.
Regular polygons
A shape with eight sides is always an octagon. If all angles and sides are equal, it is called a regular octagon.
Six sided shapes are called hexagons. If all 6 sides are the same size, then the shape is called a regular hexagon.
A shape that has five sides is called a pentagon. A normal pentagon has all five sides that are the same length.
irregular quadrilateral
That depends on what you mean by "diamond shape." In a general shape, no, the sides need not be exact. If the shape is distinctly called a "rhombus," then mathematically speaking, yes, all sides must be equal, per the definition of a rhombus.
A 3d shape with 10 sides is called a decahedron. I have added a link with some pictures of them. As you can see they look very different but all have 10 sides or faces.