Each individual item is a grammar point, it’s just that the default is to learn 3 grammar points at a time and then quiz on them (in the settings you can change the batch size to anywhere from 1 to 10 at a time). One set = 3 grammar points. 3 sets = 9 grammar points
If you feel like you can handle 9 new ones each day, go for it, but you don’t have to
I am already having 45 reviews a day, so I will stick to 6 items per day and see my accuracy.
So far is N5 only.
Is there a way to include a search bar in main page so I can easily look for an item?
Now I see I have to go to ‘all lessons’ and then I can searh for an item.
Ooof! Depending on your current level I wish you the best of luck 
(Though if that is actually an amount you can manage all the more power to ya!)
Not that I know of, but I have just bookmarked Grammar Points | Japanese Grammar SRS to quickly look up stuff Might be a script that does it, though I haven’t come across it myself.
I got scared now for your words 
is it already too much 6 items a day?
Yes, basically a script would be fine showing a search bar right?
It really depends on your level and stuff. For NEW grammar points (that you aren’t familiar with or haven’t really encountered enough yet) it is A LOT. If it’s just a sort of review (let’s say you are N3 for example, N5 would be EASY at 6 grammar points per day, N4 would be quite manageable, N3 would become difficult, and adding grammar above your level would be my personal concept of hell )
It’s mostly because you need time to internalize the grammar, potentially read up on it from multiple sources to gain a deeper understanding and have the chance to encounter it in the wild (or targeted look-ups).
But as I said, mostly depends on your actual level. And it’s always do-able, but you might get low accuracy on reviews, and if you have ghosts enabled on the strictest setting (which I personally recommend, but that’s up to you), the number of reviews can quickly spiral out of control.
For example, I consider myself very familiar with N5 grammar, but reset on the 16th for a strict, no typos and able to think of all alternatives run through. It still took me up to today to run through all N5 grammar points, as I didn’t want to overwhelm myself. So that would be like 4 - 5 grammar points per day roughly.
Nah, nobody knows what your ideal item count per day is.
As long as you feel you are spending enough time to understand each, add as many as you think are good. And if you ever feel overwhelmed, start adding less.
when we do reviews, and get correct all items, shouldn’t at the end show 100% correct?
I just did 2 reviews and got them right and still showed 92.66% correct. Something am I missing to pay attention?
I believe it shows all reviews done in the last day and uses that to work out the percentage
The problem is that there is a lag between starting items and when the reviews hit you. So although there is a review forecast this does not (I presume) take into account how many you are getting wrong - the more you get wrong the more come back to review. So if you are already struggling, then dumped with a huge pile of reviews and are unable to clear them then it will just go on getting bigger and bigger, which can be quite overwhelming. Then you have to stop taking new items and just focus on clearing them and that can be a bit painful, especially if you’ve got other things to manage in your life.