második kérdésedre (én NanDub-ot használtam, bevált):

A) If the difference between audio and video is constant throughout the video:

Load the file into VirtualDub, VirtualDubMod, or NanDub.
Set BOTH "Video"(VirtualDub, VirtualDubMod and NanDub) and "Audio" (VirtualDub and NanDub - VirtualDubMOD>"Streams>"Stream list") to "Direct Stream Copy".
From the "Audio" dropdown menu, select "Interleaving" (For VirtualDubMOD, rightclick on the listed audiostream and then select "Interleaving")
Under "Audio skew correction", set an appropriate number of milleseconds (positive or negative) in the box labelled "Delay audio track by"
Save with a new filename