I just had a few questions.

So in the description it says "stop where it says end" but there is no end screen. If there is it is the credits after completing the last level. What I have played you can't 100% the game before finishing the game or in 1 run. You will need at least 6 Jawbreakers left at the Gumball Machine. Just wondering if it stops when you purchase your final jawbreaker.

Also I was wondering if we can add individual levels since once you beat the game you unlock the level select in the game. Also, it doesn't take away any story mode on it so it shouldn't affect regular runs all too much.

In my opinion for 100% you should be done when you get everything. So you wouldn't need to beat the game twice.

No not beat it twice, you already beaten the game but now you have a level select screen to go back to levels and get coins to buy the rest of the jawbreakers. But, once you beat the game it kicks you out to the title screen and also the last level as well i believe.