I want to build the front hub myself what (or at least try lol). What length spoke should I get according to the calculator? I am thinking 286 mm. Can someone verify?

If I was using a double wall rim, I'd round up.
Single I'd round down.
Either should be fine and may be more of what lengths do your desired spokes come in.

It's a velocity fusion 700c and the front hub is Velo Orange Cru track.

The Fusion is a double wall rim.
Some spokes are only available in even or odd lengths.
That may the "decider".

First wheel? I'm too lazy to check out your answers, but considering who your responders are, I'd trust their judgement.

Smart move to double check spoke length 1. Starting with good components for your first wheel build will eliminate a lot of issues. 2. Don't be in too big of a hurry to bring the wheel up to tension. Build up the tension in small even steps to keep the rim round as you go.

Just do it! You'll be fine.

Spoke Calc gives the same length.

Measure the rim ERD yourself. Don't go by what's listed on the internet. This advice comes from unfortunate experience.

Yup. This is true even of a trusted brand like Velocity. I have found variations from published data more often than not.