vdub 1.3c will handle a lot of those files ,, the later after 1.3d version they had to take out the wmv handling as microsoft told them to they didnt like there format included in vdub, so maybe look for older version
to use it load the file in question open video/filters then add theres a vast array of what you wish to do ,, you can add a title in place of the movie segments/frames or go to bottom and you will see clipping there you can take out the frames it will reduce file size and you can encode it to what ever format vdub and you want to achieve.
like ive said doom.org and videofile helper ill provide step by step guides for all your above q's the converting and cropping of the frames its really esy to follow there directions.
good luck