Editing a 640x480 mp4 in premiere CS4 I have a video with 640x480 resolution, which I want to import into premiere and add a MASK over specific areas which should not be visible.

I'm wondering what settings I should select when I start my project.
Additionally, wondering if there is a better way / program. Basically I want to have te final result with minimal loss of data from re-compression and minimal creation of artifacts etc..

My video has the following characteristics:

ID_VIDEO_ID=0
ID_DEMUXER=lavfpref
ID_VIDEO_FORMAT=avc1
ID_VIDEO_BITRATE=0
ID_VIDEO_WIDTH=640
ID_VIDEO_HEIGHT=480
ID_VIDEO_FPS=1001.000
ID_VIDEO_ASPECT=0.0000
ID_LENGTH=10970.24
ID_SEEKABLE=1
ID_CHAPTERS=0
ID_VIDEO_CODEC=ffh264
ID_VIDEO_ASPECT=1.3333


The Media Information from VLC is the following:
A custom resolution of 640 by 480 with square pixels would work.  It's also worth noting that if you import the video and drag it on to a new sequence, Premiere should offer to automatically adjust the settings for the sequence for you.