I’m a native sketchup user. I’m new to Rhino, and has tried to make some stuff there. So I’ve got confused with the analogies.
What are the best ways to adapt to rhino?
what type of stuff/shapes do you mostly model in sketchup?
did you mainly use keystrokes or menus or icons to change tools?
Currently I’m making an object for CNC. I’ve tried to extrude a certain surface(I actually don’t know what to call it because there are so many name of the similar polygons (poly surfaces, mesh, solid), and failed. I’ve followed this tutorial from Rhino to extrude/push up the surface and having a hard time which is first I have to explode, then split then push. I can’t seem to snap the extruded polygon to a nearby object even with the Osnap on.
Note that I’ve used Autocad before, so I’ve got the basic idea how to handle the lower ribbon menu as well as the polylines and such. It seems the way to click is very different and awkward than the other software I’m used to.
Do I have to work with 2D first then 3D or there’s another way around?
I’m not a Sketchup user but from what I’ve seen, you would probably make heavy use of the gumball to work on an existing solid. See this video for an introduction:
In addition to that, you can use SplitFace to cut one face of a solid without having to explode it first.
And, of course, you need to spend some time to get the type of objects straight 
Mostly, you will be working with NURBS surfaces in Rhino - as opposed to meshes. The term polygon we reserve for meshes (unless you are drawing a polygon - a curve!). When you join two or more surfaces together, you get a polysurface. When a surface (sphere) or polysurface happens to be closed, you can say that it is a solid but Rhino doesn’t really care if things are closed or not.
How do get an extruded surface to snap with it’s neighbour in a parallel extrusion?
There are many way of doing things in Rhino so it’s not easy for me to see where you are or what you are doing that makes this an issue.
If I have a box and a plane next to it, at the same level as the base of the box, I select the plane, call ExtrudeSrf and just move the mouse pointer anywhere near the top of the box with - among others - the end, int, and mid osnaps turned on. Does that not work for you?