Except for maintenance purposes (which the landlord should notify you of ahead of time), the only one who can turn off the electricity is the power company. If the landlord refuses to turn the electricity back on, you have been constructively evicted. See the Related Questions below for information on how to proceed.
yes
no you can have one just check with your landlord first if you have an apartment
Sounds illegal to me, wherever you are. Certainly illegal in Canada.
It's bribery, which may be illegal
It is not illegal to charge more for electricity that for what you were charged. You should look into your agreement you signed with your landlord to make sure what the agreement states.
This depends on whether your landlord is responsible to ensure everyone gets their mail. If you are living in an apartment with a separate apartment number, then there should be a mailbox for that apartment, and the landlord should not have to look in the mail to see to whom it is distributed. But if you are living in some type of communal environment, or a hotel/motel, then the landlord or innkeeper must sort through the mail to deliver it properly.
It's not illegal. It might be a bad idea, though.
In order to remove someone from your apartment, you will need to obtain an eviction notice. Without an eviction notice, it is illegal to remove the person from the premises.
NO
Your landlord will win the lawsuit by default. Then a writ of restitution will be entered, and you will be forcibly removed from your apartment.
It is not illegal but it is up to the landlord or owner of the complex to decide whether or not they want to allow this. Check with them before doing any work. Some are very anal about oil spills and whatnot.
Uncertain what the questioner means by "illegal" apartment. If the place you were living was not licensed as an apartment/boarding house/rooming house the landlord can probably be charged criminally for operating an un-licensed establishment. You may have no choice but to sue this person in civil court but will have to be able to prove that the person rented you the space KNOWING that it was hazardous.