Help needed with probability math questions

How many ways are there to arrange the letters in the Word SIERPINSKI? How many arrangements begin and end with the letter S? How many ways can 12 people line up if Joey and Sallyr must be next to each other? If the same group of 12 people set at a circular table. how many seating arrangements are there? (Note the restriction that Joey and Sally cannot be next to each other does not apply to this part of the question}