@Bill That shape of table usually requires a rectangular cloth if one is purchased as what is commonly referred to as oval can tend to hang weird on the ends. However, since you are making this one, you have the opportunity to mimic the actual shape. A 12" drop is my favorite - long enough to hang nicely, yet doesn't get in the way with sitting.
As for hems, I usually only do 2 kinds. For more casual cloths I do a double turned 1/4" shirt tail hem, hand basted in place first and then machine stitched like a shirt tail or - for more formal cloths, I do a 3" drapery hem. That's a 3" double turned hem to add weight for hanging and then hand hemmed to make the stitches invisible. I usually only do this with heavier fabric which means I make the cloth fitted for square cornered tables only. I did make a round cloth once that used a 2-1/2" facing, attached with the machine, turned and pressed. This was for a 20"diameter night table.
As for machine stitched, overcast rolled hems on store bought cloths - I bring those home, cut them off and redo a 1/4" double turn. I just think those hems look cheap and they don't hang as nicely. But that's just my interior design background coming thru.