Isomerism

Methylenomycin A is a potent antibiotic isolated from Streptomyces violaceoruber. Answer the following questions about methylenomycin A.

i) Identify the stereogenic (chiral) centers in Methylenomycin A. Determine whether each is R or S as drawn above. Clearly mark R or S next to the stereocenter .
ii) How many stereoisomers of this molecule are theoretically possible? How many are practically possible? If these two questions have different answers, explain.
iii) Draw the enantiomer of methylenomycin A. Draw a diastereomer of methylenomycin A. Draw the enantiomer of this diastereomer. Draw a constitutional isomer of these molecules
iv) How many sp2 carbons are in methylenomycin A? Star them. How many units of unsaturation does methylenomycin A contain? Draw a constitutional isomer of methylenomycin A