Last time I played this game was about 2 years ago, but I'll try to clear out some of your doubts.
It keeps saying after a race that I can enter RIV if I do such and such. What the heck is RIV ??
That is a Race-Class in ENTHUSIA LIFE (EL) mode. IIRC, you start at R I, then R II, then R III, then R IV, and the hardest class of races is RS.
You must understand that this game, in EL mode, works according to a "calendar". In that "calendar", you have "weeks" and you can do one race per week.
Weekly races from R I to R IV are randomly picked and you can choose one of several presented to you (can't remember how many, I think they are 5)
In RS, however, you have a pre-fixed calendar and you have one race per week. Last week of the year you get the allmighty "KING OF THE YEAR RACE", at the Nordschleife.
To be able to race in the "next" class of races, you must reach a pre-defined slot in the rankings (again, this is what I remember).
How do you move up the rankings? By your results, of course, but there's a catch. It's the last TWELVE results that count.
Also, the points you get in each race depend, of course, of your finishing position, but in Enthusia (and this is another of the reasons why I still love this game), that ISN'T ENOUGH. The game takes into account two other very important aspects:
1 - How clean you were (and yes, it's annoying to lose points because of the AI, but that's life, remember Sutil being rear-ended by Kimi in Monaco last year

)
2 - How does your car compare to the opposition. When you chose the race to enter (of those available in each week), you have a number below each of the possible races "check box". That number represents the odds of your car. The higher they are, the hardest is the opposition.
But this is very important, because the points given in that race are, after you finish it, multiplied by that "odds" number.
So, (as an example) if a race gives you 500 points for 1st place and 300 points for second place, if you win it with the odds set at 3.0 you will win 1500 points (500 x 3.0) . But if you finish 2nd with the odds set at 10.0, you will get 3000 points (300 x 10.0).
This system is set in a way that will indeed make it impossible for you to move up the ranking using supercars to crush the opposition.
And as for limits..EVERY race, pretty much no matter what, I lose Enthu points. I'm not worried about it cuz I know I can get them back by knocking out a week and using Rest, but do I run out of time ?? Or I'll never run out of races before the big final one, for rank 1 spot ?? From what I read, getting Rank 1 means beating out the game.
You'll never run out of time, when one year ends, a new one begins. About resting, you don't need to do that on your own. You will be forced to rest rest in one of two occasions:
a) you got totally depleted of Enthu points. The game will force you to a rest.
b) you change car. That also will make you lose a weekly race.
And you do not "Beat" this game by reaching position 1 in the rankings (nothing happens when you get that, so don't be dissapointed when you are waiting for a podium ceremony and the game keeps as if nothing happened). That would be too easy

. You "beat" (at least, the EL mode) it by
winning the KOTY race. That's not easy, I tell you, and you'll probably lose loads of Enthu points trying it.
Besides, you can only try it every 52th race of each year, unless you cheat and don't save the game after you ended the race.
You will need to be prepared for the KOTY race. To be able to enter it, you'll need to reach the final week of each year placed at least 6th in the rankings. To be able to win it, you'll need a good "road" car, but don't pick a supercar, or else that's what the AIs will pick also and they'll crush you. Try something like the BMW M3.
I'm more of a GT expert, so I bump cars occassionally. The thing that's REALLY wrong, is that if you're in the lead, not sure what speed to take a corner at, if your opponents hits you FROM BEHIND, you STILL lose points. So what the heck ?? Am I doing alright here ?? Is this really that easy ?? Please respond so I know I can save it, l0l0l0l, thanks !! 👍
GT experts got used to win races and get their trophies/championships with reckless driving, bumping their way up to first place (I'm not bashing you or anyone, that was my "driving school"also before I played Enthiusia). This game is different and will make you a better driver (even in games). About the AIs, they're still better than what GT gives us, but they're far from perfect. Live with it, it's not that hard.
IIRC, if they bump you on a side panel at all, you're at fault and lose points (which is a bit silly, yes). You can basically "win" at your own speed and your own level of challenge, where winning is defined as becoming King of the Year (or some title like that) and getting ranked #1.
Just a slight correction and I'm saying this by memory so I'm not completely sure. If your car and a AI car touch side by side you'll only lose points if your car is touching the other with it's front-side panel (from the door onwards).
Again, getting rank #1 means nothing to the game. You will beat it by winning the KOTY race, regardless of ranking position.
That sucks too, you can't have a garage, absolutely CANNOT. They "tune" for you, but I never get more horses. With Level 2 Tuning, not yet..when I unlock a ride and try to pick it, when I look at mine again it's already "Special" and tuned, but I guess you can't get it back once you get your new ride..
You have a garage, you just don't "Buy" cars, but all you unlocked are there for you to use. Some of the tuning levels give you more power, some give you more grip (better tyres) and some (again, IIRC), make your car lighter.
However, each car "levels up" independently so when you change to a car you never used before, you will drive it at Level 1.
I used to get rid of each car and move on to another as soon as I got it to Level 10. Therefore, when (and if) I was able to enter the KOTY race, I had plenty "Level 10" cars to chose from.
Hope this cleared some of your doubts, have fun! 👍