There are 2 songs on my playlist I like to hear, and I like the way you can select the next song and let foobar automatically play that next song. But I would like to have it that if I select multiple songs on my playlist, I would shuffle or repeat those selected songs, instead of going to next song on playlist that it does now.

I believe this does what you want (although track changes aren't very smooth :[ ).

Yes, exactly that
thanks Chun-Yu, you saved my day