Great chemical engineers!

Questions for the house:

Can a catalyst, to be tailored for a particular use, be synthesized in the lab?

Does catalyst in any way affects the enthalpy change of a chemical reaction as compared to the same reaction, not catalyzed?

Is there any connection between additives and catalysts? any difference?

Can additive in a reagent affect the enthalpy change of the combustion of the reagent( oxygen + reagent)?

I'm faced with a (self)project I wanna carry out and I think the answers to these questions are stepping stone to my discovery.

Pls assist me as I await your comments. Thanks.