Plugin development Issue

Dear Sir/Madam,

May I know whether the Premiere Pro SDK supports the following operation on a sequence?:

1. Adding an imported media (video/audio) files on a track, and specify the start time

2. Retrieve the markers information from a clip on the track

3. Assign (Replace) a media (video/audio) file to an existing clip defined on the track

If those above operations cannot be implemented by the SDK, is there any alternatives (Extension Script?).

Thanks a lot!

Regards,

Stephen Lee