Is it dumb? No. Will you likely want to wear them or find this a fun project? Dunno.

The insoling leather looks fine. What are you planning to punch the holes with? How are you planning to cut/shape it?

With the thread, I'd go for the first link. The second is for if you were working on the uppers. Tiger Thread is a pretty popular brand. I am sure you can find it closer to you, but here's a link. Again, what are you going to use to sew it with?

The soling you've linked is significantly thinner than what you had on there. It's hard to see in this pic, but the Vibram 2021 for example is a very soft wedge sole. It's more similar to what you had on originally (softness) but is a wedge shape, rather than a defined heel stack (like the crepe was). If you really want a sheet rubber, I'd recommend perhaps a birkenstock soling knockoff, as at 10mm, it's gonna be way comfier than the 4mm rubber you linked.

Please do not use shoe goo. You most definitely need contact cement as you linked there. Barge is another common brand for beginners/hobbyists.

Remember, before you glue any surface, you need to sand it. So for example,before you stitch the insole to the upper, make sure it's been sanded on the bottom. Otherwise, when you need to glue the outsole on, you'll sand through your nice stitching trying to get it on. Shoe repair and shoemaking are two different skill sets - but both require you to think two steps ahead, or you'll paint yourself into a box.