Opinions will vary. As you progress, use boats in different situations, see other boats, talk with other builders, etc. - your opinions will vary too.
"Filling the weave" adds weight, and each successive coat adds some strength. Albeit, probably less and less strength. I like the floor of a boat to not be glassy and slick, so am not very interested in completely filling weave where I want traction.
Running some glass part way up the side of ribs will strengthen those joints. And, joints are traditionally weak points in structures.
A useful technique to use with those clear, plastic cups, is to use two at a time. Here's how. Stack two cups together, one inside the other. Put a strip of tape up the side of the outside cup. Set them on a level surface, and pour an ounce of water into the INSIDE cup. Mark the tape, and lable it as 1. Do the same, ounce by ounce, up the side.
NEVER put epoxy in the cup with tape on it. ALWAYS put a new, clean cup inside, put in resin and hardener into the inside cup, using your precalibrated marks on the outside cup. For smaller batches, you may need to have some 1/2 ounce marks. Use measurement to establish these; don't try to eyeball it. The sides of the cup aren't straight, but sloped. Volume isn't directly proportional to height.
Use a clean cup for every batch. Reuse the outside cup a lot of times. Once in a while, I use one of the clean cups for an adult beverage. But - only under duress.