designs copyrights copycats and the like

I'm starting a business. In this I will be producing some decorative items (home interior items) of my own design. I need some advice since I know nothing of what is copyright-able or not -- Or whether there is any point worrying about it.

If I have an original design, lets say for a accent lamp. Can it be copyrighted or licensed or in anyway protected from others producing a lamp that looks exactly like it?

If my lamp or someone else's lamp is produced overseas, is the answer still the same? (do the copyrights we enjoy in the US prevent other countries from copying??)

If there are elements of a design made by another individual that are incorporated into my design (but still noticable) am I prevented from copying that part? How would I know if it is a protected design? What happens if I produce a knock-off of someone else's design (as long as I do not state the designers name) - what would happen to me or my company?

If any of you out there know answers...please let me know. I may just be in left-field concerning myself with ridiculous matters.

Thanks!

Marti