What is the maximum number of stereoisomers possible for discodermolide?

What is the relationship between the two structures shown?

The product of the reaction is:

Isomers have the same ...........

The correct statement$(s)$ about the compound given below is(are):
$A$. The compound is optically active
$B$. The compound possesses centre of symmetry
$C$. The compound possesses plane of symmetry
$D$. The compound possesses axis of symmetry

What is the absolute configuration of the following molecules? ($NS =$ the molecule has no stereocenter) Note: For the purpose of this question only,the order of stereocenters is not specified; i.e.,$R, S = S, R$.
$(I)$ || $(II)$ || $(III)$ || $(IV)$