The AM/FM cassette player that comes stock won't have any RCA jacks. You have to tap into the speaker wires and use an amp that has speaker level inputs or get a line-level converter. If your stock radio has a power antenna lead you can use that for the remote, otherwise you'll have to connect the remote somewhere that gets switched on with the ignition.
1999 Buick Park Ave Ultra
Head Unit: JVC KWHDR720
EQ: Audiocontrol EQL
Front Stage: Hybrid Audio Technologies Imagine 5.25 mids, Morel Maximo tweets
Sub Stage: Boston G3 10", 0.5 cu ft sealed
Amp: PPI Phantom 900.4
Rear Fill: Boston SE953 6X9's