Regarding your first question, staff members look at all of the reports you have posted when concidering an applicant for helper. Even the ones which are already dealt with.
However, reports aren't everything ya know. :p
The ammount of reports you create really does not matter too much.
What matters more, is the ratio of accepted reports to denied reports. As said in Cheez' guide, you need to show that you have the ability to detect hackers and that you are not just taking lucky pot shots on trying to detect hacking.
Also, what matters more is maturity, kindness and grammar.
If you are mean to everyone, then don't apply.
If you write short and ungrammatical responces on threads, then your probably not going to be accepted.
For example, look at how many threads staff have to look at and reply to. Every day, someone posts a thread complaining about anti-cheats, custom shields, different gamemodes, etc. Have a think about how many threads we need to respond to every single day. I would now like you to triple that number due to the ammount of conversations we get.
If someone makes a thread about Cubecraft not having a good anti-cheat and I repond like this:
"OH my gawddd!! Stawp complaining boiii!! ~ Locked!!"
You wouldn't really get a good impression of the Cubecraft staff team.
That's why you need to think of what you respond with on threads.
Although reports are good, they are really not a major factor in getting helper. You shouldn't be too worried about losing a few reports due to the reports system being new.
If you really want to become a helper, I would recommend getting yourself known well within the community and socialising with others.