Figure out what is currently on the car. Stock shocks and springs will be the best way to do so. Like that Jon said, if the shocks are blown or have a bunch of miles on the I would replace them. You might be able to find a member on here that is selling their stock suspension and can get in on that.
You'll need a spring compressor in order to get the old springs out and new ones on. Make sure the ones you get are a proper length. Stock springs are pretty long and the original compressors I rented didn't work cuz they couldn't compress the spring enough. Right now I have a pair of Autocraft ones from Advanced Auto Parts. Those worked pretty well.
Dezod S1, Dezod Catback Exhaust, Stoptech Drilled & Slotted Rotors, AEM UEGO, Truboost, Oil Pres, Oil Temp, Fuel Pres Digital Gauges
TRD Shocks, Springs, Rear Sway, Comp Clutch Stage 4, Fidanza LW Flywheel, Racing Solution RS2 Full Lip Kit
Here's the installation instructions for Hotchkis springs - same procedure would basically be followed for any spring or strut removal / replacement, so at least you'll have an idea if this is something you can tackle.
spring compressors- make sure they are the 2 separate pieces not the one in the middle.
Stock shocks and springs. If he just put springs on the car then you have the shocks. Mine were on h-techs and front shocks were blown back 2 were not. So i had to purchase replacements from partsgeek.com.
Unless you are super strong you will need help on the back. I just raised mine back up about 2 weeks ago and it took about 6 hours with 2 of us mainly because i had to manually crank the springs.. If you have access to a impact wrench i would use it. It has to be rather strong. I bought one and it was a piece. Wouldn't even get the lug nuts off. You can rent the compressors from Auto Zone or Advance auto parts for a deposit and free when returned.
I just used one of the forum posts with pictures and went at it. Get a breaker bar too. I had a pipe i could extend the wrench i used about 3 more feet and it made life a ton easier.
It really just depends. When you take the spring off the struts the center rod should have NO give at all. When I did mine The rod just sank when I compressed the spring and took the top piece off. I knew they were going to have to be replaced. I was right at 100k miles. Also, it depends on how long it has been lowered. The struts are just under more pressure when the springs are shorter so they just give out faster, simple as that. I had H-techs on mine. Which aren't that crazy low, I believe 2 in the front and 1.5 in the back. When I got down in there my front 2 struts were gone. The driver side way worse than the passenger. But my rear 2 were perfectly fine.
I would say if the springs have been on for a while, they are more than a 2 inch drop, and you are above 80k, its probably best to go ahead and replace them. Lets be honest, a kid having the car, you know he wasn't always nice to the suspension.
What I did was just put the stock springs on, even with the blown struts, kept the compressors for a couple of days extra and ordered the struts and got back down in there. It was time consuming but unless you have an extra car for him to drive or you are just sure you are going to want to replace them there isn't really a better way in my opinion.