...Does that mean 'with the grain,' as in, when using a hand plane, in order to have a cleaner cut, one wants to plane with the grain rather than against the grain. Or doesn't it matter with a circular saw whether one is with or against the grain, and their use of the phrase "with the grain" was a loose way of describing a rip cut?...That's a convoluted question. The bottom line is, when using a circular saw, does grain direction matter in any case? Do blades perform better when cutting with the grain? Would this explain why some people get smoother rip cuts?
You have asked both some very easy questions (and gotten good answers!) and some not so easy to answer well...
I teach my students to always start with hand tools...as the tools and the materials will teach you as much (I think more???) than any teacher "flapping gums" ever could...
As such, logic dictates that a table saw should be treated just like a hand plane or hand saw, so yes...grain direction most certainly does matter. Even knowing (or being able to recognize) where the top of a tree was and where the root ball by reading the grain and wood is a skill that has been lost by most but not all of us...
Now, if only a "wood machinist" for the most part and using big tools to do the brunt of all you woodworking, these details tend not to make as much a difference to the person doing the work. It's a different quality and style of work, and very often with a much different goal set and perspective of the craft. It all depends on you and your goals in woodworking.
As an example, we are very concerned with authenticity and style because we finish everything by hand and do a lot of "hand only" work with just hand tools because of the tradtional nature of our projects and craft work we do. However...our table saw is a vintage Northfield with a 18" blade on it so grain pattern is only important to us...that saw could care less...and cuts anything and in any direct with just about any blade you put into it...!!!...which also makes it very dangerous. I comment on that only because a lot of your questions have as much to do with the blade as the saw and your knowledge of application...
Good luck and enjoy the saw dust!!!
Tosa Tomo Designs
Confucius (551 BCE):
"I hear and I forget. I see and I remember. I do and I understand..." "...Real knowledge is to know the extent of one's ignorance..." Socrates:
“I cannot teach anybody anything. I can only help them think..."
"Seek to understand, before seeking to be understood..."