Does The Landlord Have The Right To Enter The Property Whenever They Want, And When There's No One Home. Or Should They Let Me Know In Advance?

No they can not. Check the state laws to where you live they can only enter if they give you a notice.it is usually a 12 hour notice but in some states it is a 24 hour notice. However after the notice they do not need your permission to enter. Be careful though private landlords have their ways of producing the notices for court purposes even if you did not receive one. Best thing in a situation like that is to set up an in writing agreement where you and the landlord actually sign the notices when you receive them.

The landlord does have the right to come in your house whenever they want to they have to call and give you notice and ask for you permission. Say if your landlord calls and ask can he come by on tuesday you have the right to say no and tell them a day good for you .

A landlord can enter the property to do repairs with your knowledge if no one is home, but he does not have the right to enter your apartment whenever he feels he wants to without your knowledge or permission.

No the landlord has no right to enter the property whenever they want.

They should not enter the property whenever they want or when there is no one at home.

They should let you know in advance.

Check out your tenancy agreement a landlord has  to give notice in accordance with that.