Can I slide out pieces of laminate and replace?
Yes, you can do that. But remember that there's a tremendous amount of friction between adjacent pieces, and getting ones that have longer edges in contact out is going to need a lot of elbow grease.

I had to do this when laying laminate. Had about a dozen pieces that stopped short of the front door (we originally planned vinyl there and changed our minds), so had to remove these  shorter pieces and lay laminate across the entire area.

It helps to cut out a notch in the piece you're removing, then slot the smaller edge of your pull bar in, and use your hammer to remove the laminate. It's a long and noisy process, but can be easily done.