Dont underestimate the difficulty, I struggled. It sticks and it's not coming off. Use soapy water so you can reposition it if you go wrong.
Yep. And do it when its warm if you don't have an indoor garage which you can heat.
It not as easy as the DIY signage firms make it out to be. When I was in the trade a customer sent decals for 3 x LWB vans he had ordered. The decals arrived in the afternoon and the van were due out the following morning. I stayed behind in the workshop to stick those decals on as we couldn't find anyone to do it at short notice.
I finished just after midnight.