As I understand it, the left homing machine is a zig-zag machine. When it's not zig-zagging, but straight stitching, it sits on the left side of the zig-zag instead of the middle, if that makes any sense (homes to the left side). I've not had one, but I believe that because it sits to the left, it's hard to get an accurate 1/4" seam when you piece a quilt.
The 15 clone should do well for you. It appears to be in good shape. Generally speaking, they don't take any professional service. You are able to clean and oil them yourself with the manual referenced below.
Here's a
manual for 15 clones, writtten by Bill Holman, a legend in the vintage sewing machine world.
bkay