if you are using Acrobat professional 6 or above there is an option PDF Optimizer under advance, u can use that to compress your file size

play around with it setting to get the size and quality that you want

yeah u can insert video, under advance editing

i dun usually edit pdf document, i always edit the source of the file either quark, illustrator, etc thn convert to pdf

indesign is fine, i think it's more user friendly that quark but i haven't start to learn how to use indesign yet so i not sure how good izzit, but i have heard good things bout it

if you are doing artwork with more than 1 page indesign or quark is the way to go, for my work i use quark and use adobe distiller 6 to convert to pdf files, even for the final print file we'll use pdf since our overseas printer prefer that. most local printer dun use pdf though IINM