You can buy proprietary brands of sugar syrup, or if you'd prefer to make your own, I recommend making a 'rich' two parts sugar to one part water (2:1)...
Regarding point 5 above, high temperatures do indeed cause rapid hydrolysis of sucrose into glucose and fructose *in the presence of mineral acids or invertase* (enzyme):
It may be just “exponential kinetics”, but the maths and science in the links are unfathomable. Are you saying that in the process of making a rich sugar syrup, even with prolonged boiling, there will be NO conversion to glucose and fructose? Or just minimal conversion?
https://qsstudy.com/first-order-reaction-hydrolysis-sucrose-glucose-fructose/
but only incredibly slowly in a simple water-sucrose syrup:
https://chemistry.stackexchange.com/questions/116764/how-long-would-it-take-for-sucrose-to-undergo-hydrolysis-in-boiling-water