Hello Everyone!

My name is Jake, i am a fabricator only just getting into the world of CNC! a brief background on myself:

Time served fabricator with experience in the Agricultural/Heavy Plant/Motorsport industries, having also worked in a foundry as a maintenance engineer.
ive most recently worked at Prodrive/Aston Martin Racing building Vantage GTE/3/4 race cars, primarily installing the roll cages and doing the shell prep + the space frames for the BRX Dakar racers.

That has led me to want to build myself a CNC Plasma tube notcher as i run my own business designing/fabricating/installing roll cages amongst other motorsport fabrications. Naturally ive been doing some research and there seems to be plenty of information out there but not so much in the UK when it comes to this type of machine. i have experience using Bendtech & Fusion 360 but im by no means a CAD/CAM Wizard...

i plan on building a machine around 3m long with as much X Axis travel as possible, in which it will be a 3 jaw chuck driven rotationally. and then a plasma torch in the Z Axis that moves to suit tube diameter.

i have a few questions that have sprouted since researching if anyone could be so kind to help with!

Mach3 the best software in this application?
Rack & Pinion over ball screw?
What spec stepper motor is advised? Nema34?
HF Or non HF start plasma cutters?
Good suppliers for parts in the UK?

Any help would be massively appreciated!