Hi all, first actual post since the intro

So I'm one of a wave of people that have no doubt bought portable WFOs off the back of lockdown since we can't get out to restaurants and just because, well, I wanted one dammit!
Mine arrived over 2 weeks after ordering with a broken 1cm stone

After much to-ing and fro-ing with Amazon, I'm finally getting a replacement delivered - it's slightly too big for the oven though.
My first question on this point is how does one cut cordierite without breaking it? The second is, the old one had a 1cm gap around it to the inside wall of the oven and was raised 1cm from the base by standoffs. Was this for convection purposes or should I just get the new stone cut to fill it and make biggers pizzas?
My next bit and onto the title of the thread is this. In between trying to sort a replacement with Amazon, I got concerned that it was not going to end well for me so I started to look at replacing at personal expense. That's when I stumbled upon pizza steels, the ones I liked were 0.6mm or 0.8mm thickness. I mentioned this to my father who I'd completely forgotten worked for a steel plant so he's getting me one. So, now I have a new 1.5mm stone coming and a 0.6mm steel, which will perform best in a oven capable of getting to 400
oC (~750
oF)?
My thinking is that if the steel does the job, I can sell the stone or keep it for big pizzas on the BBQ. However, if stone is better then I can use that in the WFO and keep the steel as a hot plate for the BBQ.
Thanks in advance!