You can piece by serger, there are some books out on doing so. Seams are bulkier, though. If the seams are in something like clothes, then a serger is great. I use a standard sweatshirt pattern, make a quilt top big enough for front and back, line it with flannel and finish with lightweight muslin. The inside seams get serged and so does the ribbing on the neck and sleeves. Looks much better.
Serged overedge can be snagged or cut by careless user. Usually just serge over fixes.
All kinds of sergers around. I'd go look at every dealer you have available, and check on how the serger threads. Some older ones can be a real pain. The self threaders (All Babylock) are very nice, but more expensive. Since I also make a lot of clothes, getting one was worth it.