Alibre xpress has changed slightly since the pre 100,000 post 100,000 thing.
I think now if you download the software and run it you have one feature set and assembly total different parts limit.
Then if you register the software you get a bigger number of assembly parts, and you also get some other features, perhaps 3D sketch, shell, import export like the first 100,000 I'm not sure.
Xpress will open big assemblies, created in the full version, as read only - so it is the ultimate viewer with the ability to edit individual parts from the big assembly. you can send youre stuff to anyone in the world and they can look at your design in 3D on free downloaded software.
The next version of Alibre is due out in the next month or two and there will be more features and the difference between xpress and the full version will change no doubt.
However, if you are balking at the price of the full version (US$995 for Alibre std) because you need more assembly parts, bear in mind that they will sell you added features bit by bit so you can get the part limit lifted without paying the full wack. Consider that before you go to some 2.5D non parametric system!
By the way you can draw 2D in the drawing workspace and export that as DXF to get your quick toolpaths, or you can model it in 3D and export dxf from the 2D views of it.
If you did it in 2D you can still use the geometry to extrude into 3D later if you need to.