Welcome to the Bunnings Workshop community. Thank you for joining us and sharing your question about how to choose a mitre saw.
When choosing a Mitre Saw, I always recommend looking at the features that will make the job easier. A spindle lock allows you to change blades quickly. An LED shadow line or laser guide will help with precision cutting. A dual bevel feature will let you cut timber without having to flip the timber piece over. A compound feature will let you extend the cut of the saw to a much longer length than an ordinary mitre saw.
The Mitre Saw Blade also plays a role in the quality of the cut. A quality blade will provide a longer service life and make cutting timber a much easier process. There are also sets that come with a mitre saw stand. This allows you to cut long pieces of timber without having to set up saw horses. It sounds like an extensive project. Any updates you can provide while building it would be much appreciated.
Let me tag our experienced members @TedBear and @Adam_W for their recommendations.