@camontellano said:
Does Someone know where to start reading documentation on how IFC Aligment works?

I recommend that you start at the very beginning - the very best place to start: IfcAlignment.
Alignments are described via two separate but complimentary mechanisms: business logic and geometric representation. The former tends to resonate with industry practitioners and domain experts whereas the latter is more familiar to those with previous experience implementing IFC.
Are objects simply placed along an Alignment can they be sweeped between two positioned profiles?
Both! See IfcLinearPlacement and IfcSectionedSurface.
Are horizontal and vertical Alignment separated from each other.
Yes:
Horizontal: IfcAlignmentHorizontal for business logic and IfcCompositeCurve for representation
Vertical: IfcAlignmentVertical for business logic and IfcGradientCurve for representation
Cant: IfcAlignmentCant for business logic and IfcSegmentedReferenceCurve for representation
What types of curves are supported or how are they to be described?
Review the documentation on Segment Type enumerations such as IfcAlignmentHorizontalSegmentTypeEnum
Any help here would be very greatly appreciated.
Hope this helps!