-Can i model this in revit itself or are the tools in revit so limited or take a lot of time to model so that i have to bring this from an external software?
-In what software do they model these(Pictured above) and how do they bring it to revit(format...)?
You can model it in Revit but it is not easy. At all. What you show maybe modeled in 3DMax or Rhino and meshed out to DWG and finally imported in the Revit RFA. Most of them are done this way. If you are lucky you can find some pieces were done directly in Revit like the picture below (click this link) or some are imported but as clean 3d solids instead of messy meshes.
IMHO if you are not a furniture designer then I see no reasons to model what maybe available from some manufacturers. They may not be perfect but enough for planning and delivering the design intent. And if your work is designing furniture then no Revit is not the right choice. I know some folks favoring model them in Revit and I respect their enthusiasm and skills, but it isn't for me.
It really depends on your intention. Most people who are doing rendering will import objects from other software to revit just to achieve the render look they want. Most often for the project, high 3d model don't add any value. You can certain built it. I've built Delorean car just to test out the capability & the usefulness. At the end I end up having 100MB+ family which isn't really practical. It just looks cool that is it.
