Chemistry: My question is how does a greater concentration speed up particles and cause collisions? 2nd question: How does a catalyst impact any results taken?

Simply increasing concentration does not increase the speed of the particles, it increases the rate of reaction. The greater concentration of particles makes collisions more likely. You can think of it as the particles becoming more crowded together so it’s easier for them to ‘bump’ into each other. More overall collisions results in more successful collisions (where there is enough energy for a reaction). This is what increases the rate of reaction. A catalyst increases the rate of reaction. They do this by lowering the energy required for a successful collision, which again makes successful collisions more likely.