I love my serger!
Sergers are great for sewing knits, which you obviously use for skating outfits. A serged seam has some stretch, so you don't have to worry about stretching the fabric with your hands and using a zigzag stitch like you do with your regular machine.
Sergers can cut the surplus fabric as you stitch, but you can disengage the knives if you don't want to. For patterns by companies like Kwik Sew that have 1/4" seam allowances, I prefer to disengage the knives, since my serged seam is already 1/4" wide and there's nothing extra. (I think Jalie also uses 1/4" seams, but I'm not positive. I'm guessing you'll use either Kwik Sew or Jalie for skating outfits.)
A basic serger will sew seams with 3 or 4 threads. A really nice one will have 7 or 8. Mine is a 4 thread machine. I use 3 thread stitches for rolled hems and other decorative stitches, and I use 4 threads for sturdier seams on the inside of garments. You can't do a traditional hem with a 4 thread serger. I can do lettuce edging and things like that, but if I want a regular hem where the fabric is folded over and stitched, I have to go to my regular machine.
The really nice ones with 8 threads will do a coverstitch, which is what you see on the hem of a t-shirt. I've never seen one in action, but apparently it does an overlock stitch at the fabric edge, folds the fabric, and hems it all in one pass. I do know people who have one, and most of those people actually recommend that you get a more basic serger PLUS a coverstitch machine if you want to be able to do that. The reason is that it can take a while to convert the machine from doing regular serged hems to doing a coverstitch.
I strongly recommend that you check out the machine reviews on
Pattern Review before you make a purchase. You can see what other people think of their sergers, and there are message boards where you can ask questions, too.