Sergers are great machines and I couldn't make garments, curtains, etc., without one! They do a beautiful rolled him on ruffles, finish seams so they don't ravel, are great for sewing knits, as the stitches give and don't break, and some can do decorative stitching (as in a flatlock stitch). I'm not sure which model of Singer this is, but I agree, some of the older ones are better than the newer ones. I have a 20 year old Pfaff that is going strong.
If you don't have a book, don't unthread it! When you want to change threads, cut your thread near the spool, tie the new color onto the thread and sew or pull it until it comes out the throat plate. Of course, at the needle, you'll have to cut the knot and rethread the needle.