refinishing an old coffee table
Let me start by saying, I have refinished my share of furniture. What kind of top coat is that? To me it just looks stained and maybe shellac. How old is it may determine the top coat. Are the black rings on the top coat? 
First, I would not use stripper. Makes more of a mess than worth it. I would just clean it with mineral spirits, let dry and sand. You can use a random orbital or sheet orbital is ok to use during resurfacing but ensure to progress threw the various grits. You can use pre-stain conditioner but that is usually for new wood, not refinishing, unless you have removed all of the stain (very hard to do) and you are doing a major color change. I.E. Dark to light or light to dark. Depending on what you use, you do not sand after each coat of finish only fine steel wool or very fine sand paper (hand sand only). Top coat finish is a personal preference. I use oil-based polyurethane for all of my projects because of the durability, takes a little longer but worth the effort. 
I hope I helped and good luck!