Why are we using property 08 and not property 09?
wiki wrote:
By overriding an old type, you're saying "my type is a substitute for that old type"[...] For example, if you want to replace the old coal mine with something that changes its coal production more dynamically, use property 09 to override industry 00. This way, other industries that want to be far from coal mines will stay far from your industry type too. If, however, you want to replace the coal mine with a potash mine, do not use property 09. This will ensure that other industries don't consider your type as a coal mine.
I'm really trying to understand...

using 09 I use my new defined industry as a replacement of the industry indicated by ID following 09 property (00 09 <id of replaced industry>) . If I use <Id of disabled industry> 08 FF i'm disabling that industry. is it right?
and if i use <no-matter-id> 08 <id>, in our case 00 08 02, i'm simply changing the property of industry indicated by id (in our case 02, sawmill)? or better, i'm creating a new industry copying the original one and i'm changing property on the copy? if it is the case, shouldn't i delete (<id> 08 FF) the copied one to avoid the reaching of 37-industry limit?
So in my case, using property 24 on all industries, shouldn't i use property 09 to override old industries?