Hello!

1. The best URL would it be if you just put the door-handles straight from the home, less deeper. Like this:

http://doorhandle.ie/door-handles
http://doorhandle.ie/door-hinges
http://doorhandle.ie/door-locks
....

2. To optimize your Home, you have to put the minimum links you can. Put just one link for DOOR HANDLES, or for DOOR LOCKS. But you choose where to put, at the left column or the top bar. Now you have to think about your users.

When you create a www, you have to use one as the main one. So redirect this actual one to the www version using 301 redirecting.

I would recommend you also put some keywords in H1 (just one tag of these in each page), about what the page is.

And use some rel=nofollow on the links that is not strictly of your business, like support, privacy policy or about us.

Hope it helps! =]