What Speakers Should I Buy

1998 JEEP GRAND CHEROKEE LIMTED 5.9
HAS INFINITY GOLD SYSTEM
I Want To Change Out The Speakers With A Good Speaker. I Don't Listen To The Radio Too Loud. Hopefully The Speakers Will Fit Right In Except I Don't Know Any Of The Sizes. I Have
2 Speakers In The Dash Which I Believe Are Tweeters
2 Speakers In The Front Doors
2 Speakers In The Back Doors
2 Speakers On A Bar And 2 I Believe Are Tweeters

I Would Like To Be Able To Take The Old Speaker Out And Put A New One In. Has Anyone Done This And If So Let Me Know A Good Speaker That Will Do This And The Price If Possible.
I Don't Know Alot About This Stuff So If You Could Tell Me How Many Ohms And If It Should Be Midrange Or 2-way,The Watts, COAXIAL. I DON'T KNOW ANY OF THIS STUFF. TELL ME WHAT I CAN SLAP IN THERE, AND WHERE I CAN GET THEM.