Welcome to the buildingSMART community.
Some good places to get familiar with IFC and tools:
https://standards.buildingsmart.org/IFC/DEV/IFC4_2/FINAL/HTML/
https://technical.buildingsmart.org/community/software-implementations/
Will the same object always have the same id in subsequent exports?
To some extent yes:
Building elements usually have same “Globally Unique Id” (GUID) in subsequent exports from the same authoring-software.
GUIDs of element types, property sets, relations, etc. are different in subsequent exports in some authoring-software, for whatever reason.
If you try to import an IFC file to another authoring-software and immediately re-export to IFC without any manual changes (round-trip) you will get a nasty surprise:
IFC is far from perfect but it is the best what we have for software-independent model exchange of building information and civil engineering project information.
Best way to read IFC:
Take a look at IfcOpenShell, xBIM, blenderBIM,…
https://technical.buildingsmart.org/community/software-implementations/
Best regards,
Herbert