Help with cutting a fibreglass fuselage - Vario Chinook

Hi all. I am new to ScaleHeliPilot. I have recently bought the Vario Chinook 1:11 and I'm done with the mechanics. Fuselage up next. I have never cut fiberglass before so I am petrified :)

Other than some old RC scale cars (eg Tamiya) I have done in the past, this is my first journey into the world of Scale.

I noted that Michael Kranitz suggested a step bit for the 30mm landing gear holes. I am curious though about the larger circular cutouts for the rotors. The instructions suggest 75mm and 90mm diameters for those. What is the best way to go about it? A dremel would work but it is difficult cut perfect circles with a rotary. I could look at a hole saw, but I'm worried that it might rip the fiberglass.

Curious to hear what other people did.

My second question is about sliding the mechanics in and out of the fuse. I saw Michael warned that one needs to be ready to do this a lot. It seems quite an involved process. Removal of the front rotor (and re-application of loctite after reinsertion?) And I guess the landing gear must also be unscrewed from the mechanics every single time? Is accessing the front landing gear not a pain? Because I assume the landing gear struts must remain in the fuse after the mechanics slide out.

I'll probably have many more questions as this proceeds. Looking forward to some great discussions here.