Yes you can trade properties in a game of Monopoly.
Your pawn has to land on it. Or if a player has it already you can trade when it's your turn, but he has to accept or decline it.
No you can only mortgage or trade nothing else
No. If you own all the properties in a color group, you may build on those properties regardless of whether your token is on the property or not.
As soon as you start
Yes
Monopoly has 28 properties in the game. So the answer is 28 properties can be purchased during a game of Monopoly.
no
The names of the 3 Monopoly red properties are Indiana Avenue, Kentucky Avenue and Illinois Avenue.
No, only properties can get mortaged. However, you are able to sell back hotels to the back if you need money.
Mayfair
no you cannot.
no you cannot.
28 properties counting railroad and utilitys
The properties are roughly 2.5"h x 1"w
All of the properties in a set (ie., all properties of the same color)
It is so, because they sell "Monopoly" the board game.
park place and boardwalk