BD Player Oppo and UpConversion

I am somewhat of a newbie on this so hopefully the forum will be patient with me.

I am trying to decide if I should replace my current inexpensive Sony blurray player with Oppo BD-103.

I watch a mix of blu ray movies, some older DVDs and stream NetFlix. For music I am mostly use an 1st Generation Apple TV where I ripped all of my CDs in lossless format.

My TV is a Pioneer 50" Elite and receiver is an Integra 7.9.

I am little confused about which component handles what best - meaning let the Bluray player handle the video part and the receiver do it's part. However, if I do watch an older DVD would it make sense to have a " better " blurry player process the image. Similarly with blurray movies. However, someone told me that all Blurays are already 1080p so there is no processing to be done.

Also what about sound

Thanks a lot!!