donnovan86

Not sure who told you that. But they are wrong. Your gigs are shown to clients no matter if you are online or offline. 
I've been here for 11 years and guess what, I am online only when I deliver stuff or reply to clients. My gigs are always shown to clients because what matters when it comes to gig ranking is your performance, if you canceled orders, if you delivered late, private reviews you received and other metrics. Fiverr doesn't care if you are online or not. They will show your gigs to more and more people if customers are happy with the work you do.
I mean, if you want, stay online, but I am sure others will reply here saying the same, it doesn't help with anything. 

There's no way to cancel an order without negative effects. 
If the order was placed without consent and you don't offer that service, you can go to customer support. But even then, they will study the eligibility and see if the negative effect of the cancellation can be removed. But obviously that's a minor case.
Most of the time, if you cancel an order, that has a negative impact on your stats. And if you already delivered the order, the buyer can also leave a review for it, even if you canceled. 
 

Talk with a tax professional in your country 🙂

When you Google "how to join Fiverr Pro", this shows up https://help-pro.fiverr.com/hc/en-us/articles/17029281011217-How-to-Become-a-Fiverr-Pro-freelancer and you have an application link there. Funnily enough, you're the second person asking the same question today. I would hold off until you get more reviews and stuff, your account is very new. But that's my opinion, feel free to try and apply right now.