Without knowing the model or age of the pioneer system --can't answer all your questions-- it appears that it is a basic HTIB. DVD players output at either 480i or 480p. Check user manual -- see if the DVD player is set or can be set for "progressive scan" (480p) and 16x9 aspect ratio but without component outputs I'm not sure if connecting the Pioneer SVHS output to the HDTV SHVS input will give you 480p if the DVD is progressive scan. Give it a try.
You can connect the satellite digital audio out to the receiver digital in but since you have a HDMI connection (which I wouldn't touch because that gives you the HD picture) you'll have to mute the TV volume when using the recever.
Why would a surround sound system (Pioneer) only have an s-video hookup when it has a built-in DVD player? Doesn't DVD support 720p?