factory radios and cd player???

[f15xxx]

99 leg l sedan 2.2 5-sp anniv model. came stock with a P114 am/fm cassette w/o weather radio. i also have obtained a P122 head unit that is an am/fm cassette with function button for cd player.

 

the haynes book shows a late model installation with what appears to be my radio and a cd player, ie: no function button for cd player.

 

question is can a factory single-disc cd be hooked up directly to my existing radio head unit or is the P122 required? also, will i find a pigtail connector for a cd player on my existing wiring harness? if both answers are yes, i'm assuming that playing a cd overrides the am/fm/cassette automatically???

 

thanks guys.