No, it will not tessellate.
yes
A rhombus tessellates.
no
Not everything tessellates
Because all sides are the same length, and it is a regular shape. It tessellates, because if you lay squares of the same size adjacent to each other, they will leave no gaps.
Triangles, Squares and Hexagons always tessellate.
No, a hexagon is not a tessellation. Some hexagons can tessellate a plane, others will not.
No. An equilateral polygon with 5 or with 7 or more sides will not tessellate a plane.
It's one of the only shapes which tessellates perfectly (think tiles, if you tiled a wall with hexagons then there wouldn't be any gaps. Of the shapes which tessellate perfectly (triangle, square, hexagon) it has the smallest perimeter for its area i.e. a square of area 10cm^2 has a greater perimeter than that of a hexagon with an area of 10cm^2. So, if you were a bee trying to make a honeycomb then the hexagon is best because it would use least wax to make a certain area of comb (because of the perimeter/area ratio) and also not waste any space (because it tessellates without leaving any gaps). Hope that helps.
Each interior angle of a regular polygon that tessellates by itself is a factor of 360°.
All sorts. For starters, no convex polygon with more than six sides tessellates, and various polyominoes of seven or more squares don't.