Some common errors:
Point 4 Expanded:
w* = { ε, w, ww, www, wwww, . . . }
and
∑* = { ε, 0, 1, 00, 01, 10, 11, 000, 001, 010, 011, 100, 101, 110, 111, . . . }
(take a concrete example to illustrate the point better)
Let's take w = 11 then
w* = { ε, 11, 1111, 111111, 11111111, 1111111111, . . . }
∑* = { ε, 0, 1, 00, 01, 10, 11, 000, 001, 010, 011, 100, 101, 110, 111, . . . }