1) Is it OK to flirt cleavage?

How can it NOT be OK - meaning, not legal, right? The laws are to protect YOU. Since the action of flirting the cleavage is completely and solely on your part, there is nothing to protect you from. I do not know about Australia, but assuming that it is similar to the States, the government protects you from your own actions or from the high likelihood of your own actions only in one specific case - when you have a suicidal plan. Then you are placed on a locked unit against your will. That is the only situation in which the government protects you from you. Same with nudity on the nude beaches - you take your own clothes off so there is no action on his part and nothing to protect you from.

2) Is a kiss on the cheek OK? Per local laws and their interpretations. A kiss on the cheek would be an action on HIS part, and, as such, may very well not be OK.

Since your questions are very specific - cuddle, etc, I would write to your local police department and ask for their guidance.

You are hinting at having a different question altogether, though - knowing that the guy you are sort of being a little flirtatious with may go to prison for certain actions, is it OK to still be flirtatious with him, knowing the consequences for him? This is a valid question, but not a legal question. Legally, you can do whatever you want.

The question on whether it is OK being flirtatious knowing that crossing certain boundaries would land the guy in prison will remain with you even after you get some - hopefully, concrete and specific - guidance from your local police department, because if you engage in an act A that HAS been approved by the police department, you should realize that the act A might, through a more or less expected sequence of events, lead to an act B that HAS NOT been approved. So you would be tempting the guy, still. I am not saying that it is wrong, I am just pointing out that you should realize that you are doing what you are doing. Legally speaking, though, the responsibility for his actions is always on him and you are not responsible - that is a technically and narrowly correct answer to your inquiry. He should always control himself, regardless of your actions.

From everything that you have written, it seems that you are on good terms with the guy you are babysitting for and may want to visit nude beaches with, and if that is the case, you probably do not want the guy in prison... right? So probably just wait a little bit and then you can do whatever you want, without anybody going to prison.

Prior to 1991, you would have been one year shy of official marriageability...

Marriage Act 1961 (Australia) - Wikipedia, the free encyclopedia