How important is the tonearm?

I am presently shopping for a new tonearm for my new turntable. I looked at basic arm like the Jelco (500$) but also at arms like Reed, Graham, Tri-Planar all costing over 4000$.

The turntable is a TTWeights Gem Ultra and the cartridge I have on hand is a brand new Benz Ruby 3.

Here is a couple of questions for the analogue experts.

1. Is the quality of the tonearm important?

2. Is it easy to hear the difference between expensive tonearm (Ex: Graham Phantom) vs a cheaper Jelco (Approx. 500$)?

3. What makes a good arm?

Any comments from analogues expert?