Question about edit function

First off, i should say that I’m new to 3D modeling on the computer, so i have been having a few problems with it. The first problem i have been having is not being able to locate a simple function, copy/duplicate selected object. I have also been having a problem moving a selected object to another layer. when i looked it up, the default key shortcut is M, however when i use that shortcut, it brings up the mirror menu. The third problem i have been having is setting subsurf to only 1 object, when i have the object selected, subserf is applied to other planes that i have, curving the sharp edges. How do i solve those problems? Any help is appreciated, thanks.

Copy/Duplicate is shift-d to build an unlinked copy, alt-d to build a linked copy (alt-d assuming your object mode builds duplicates the object, but essentially makes the two objects link the same mesh data so that editing the duplicate also effects the original and vice versa).

To move layers you must be in object mode (‘tab’ if your in edit mode).

Subsurf is applied to an entire mesh. What it sounds like your doing is having all your planes in one object/mesh, when you should really have them in multiple ones. To separate what you have, select the planes and press p->seperate to separate the vertices out into new objects.

I tried the shift-D and the alt-D with an object selected, both in object and edit mode, neither worked. do you have any suggestions for that? what i wanted to do with layers, was move an object in the first layer to another layer. i tried tab, and that only changed from wireframe to solid. as for the subsurf problem, i decided to scrap that file, due to poly problems(too many), and started another. i was able to apply the subsurf to individual objects, however I’m at a loss to what the command is to accomplish the next step. I have 2 cylinders, one inside the other, neither with ends, i would like to combine the 2 into 1 solid mesh, with ends, so it would basically be like a pipe. how would i do that so that it looks correct with subsurf? also when i exited editing mode for 1 object and created another, i have been unable to find a way back to the edit mode of the first object, how is this done? any help is appreciated, thanks.