No. If your parents are alive you can sponsor your parents and their dependants under 22. You can’t sponsor siblings who are over 22 unless you are under the lonely Canadian rule, and you are not.
No, as said previously, if you want your sister to come to Canada, you must qualify and be selected to sponsor your parents and then include your sister as a dependent in the application to sponsor your parents. It is not possible to sponsor your sister independently.
Not until your parents passed away and you remain single (not married and no common-law spouse) and no child of your own. You also cannot have any relatives in Canada.
Then at that point, you may be able to sponsor them as other family sponsorship.