Preparing an oven for meat and dairy

To the honorable Rabbi, peace and blessings ,
I would like to ask a few questions regarding using one oven for my meat and dairy:
We usually use the same oven compartment for both dairy and meat dishes. Until now, we have been careful to wait 24 hours between cooking meat and dairy and vice versa, but we have not been careful to preheat the oven to high heat for half an hour.
Today I looked at “Pearls of Halacha”
 
https://ph.yhb.org.il/17-25-14/
And we discovered that it says you need to heat to high heat but you don’t need to wait 24 hours.
Therefore, I would like to ask the Rabbi the following questions:

1. Is there a halachic method that states that one must wait 24 hours between using meat and dairy in the oven, even without heating the oven to high heat ? In other words, does this method stand on its own, or does it have no significant halachic basis?
2. If I take upon myself the words of “Penini Halacha” – to heat the oven to high heat for half an hour between using meat and dairy – can I rely on the cola described there, and not wait 24 hours between uses ?
3. It says there that “it is customary to clean” the oven before the hachshara. I would like to understand – is this cleaning part of the law, or is it just a matter of editing? ? Because if the oven is heated to high heat, there is seemingly no need for thorough cleaning, but only to make sure that there are no visible gross residues.
4. Regarding meat-based foods, such as chips – is it true that the lenient opinion described in the halakhic references permits baking them in an oven that has consumed meat (or milk), even without preparation or a 24-hour wait ? In other words – when you want to eat the chips with a food of the opposite sex, and there are no actual leftovers in the oven – is it permissible to use them as is?

In closing, I would like to thank the rabbi for his assistance. Even when it comes to things that seem simple, it is important for me to make sure that I have understood the halacha correctly.