Yes.
Yes, you have to compress if you remove either.
if you are talking about those rubber springs yes! if they are: the new struts should come with a bolt in the box which you use to keep the rubber spring compressed. the springs have a threaded insert where the bolt threads in. if you don't good luck getting that rubber spring to compress again.
you need to compress the spring with a valve spring compressor tool, and then remove the valve keepers, and retainer.
You need to remove the head to do this . Then compress the spring and remove the keepers
You'll need a valve spring compresser, compress the spring down, toward the head then remove the retainers and the valve should slip right out.
Compress the shock spring with a spring compressor. Remove the top strut bolt. Remove the bottom strut bolt. Reverse the process to install the new struts.
If you mean suspension springs... You need raise your car. Remove the wheel. Remove the strut. Make sure that you have strut spring compressor (you can rent one at Autozone). After that compress the spring until you will able freely rotate to top part of the strut. If the spring is broken you can skip compressing. Remove the center nut. Remove the top part of the strut, replace the spring. Inspect rubber parts, replace if you have to. Align the spring. Compress it. Install the top part aligning it properly (there is an arrow showing outside direction). Tighten it properly. Release the spring. Install the strut.
Use a strut spring compressor to compress the old spring, the remove the strut from the spring. Use the compressor to put the strut into the new spring. Install the strut and spring into the vehicle.
Compress the strut spring with a spring compressor. Remove the retaining bolts from the top and bottom of the strut. Remove the strut assembly. Reverse the process to install the new strut.
The coil springs are not easy to remove or install. The spring needs to be compressed in order to be removed. It takes several hundred pounds of pressure to compress the spring.
There is a special tool that pushes down the horn plate then remove the "C" clip,then a wheel puller to remove the wheel.
Your local auto parts store will sell you an inexpensive tool that will remove and replace that spring easily. It should cost less than $20.