Plugins For and E-commerce Site

I am in the development stage of an e-commerce site and I just want to know if there are plugins already made that can accommodate our business and which ones they are. We do knobs, pulls and door hardware. I have a showroom with literally tens of thousands of different SKUs. From hundreds of different vendors. Is there a plugin that can calculate the weight of an item(s) and each vendors specific shipping requirements? The next question is that with door hardware you can choose a lever/ knob to go with a back plate. Is there a plugin to accommodate this need as well? (example; Lever A can go this back plates A,B,D or E in finishes 2,4,5 or 6 while Knob B can work with back plate B,C,E or F in finishes 1,2 or 3). I know this is all over the place if any clarification is needed please ask. All and any help is welcome.

Thank you