Problems with blender, hopefully easy to fix

So i recently began learning blender, and i am very eager to learn it, but several frustrating problems keep me from completing projects.

  1. I was watching a tutorial on how to model a human head, whenever i would hit tab to go to edit mode, my human head would be replaced by a cube.
  2. I seem to be having trouble with zooming in, and navigating. i will try to zoom in on my object, and it will only get so far and stop, it wont let me look around or anything all i can do is scroll out, i tried switching to ortho view, but that actually changed the appearance of my model, and made the camera do very strange things
    how can i fix these problems

it would be helpful to know your Blender version and your PC Operating System.

  1. That is happening with Multiresolution modfier if you do not Apply it. Be sure you have a copy of object on different layer before applying. No reverse operation.

  2. See camera clipping distances on Camera properties. Change of apperance is expected tho :). Look how default cube changes e.g.
    Selecting object and hitting dot on numpad helps sometimes to get closer. Try to apply scale, location, rotation - Ctrl-A.

Hope that solves some.

Blender 2.61
Windows Vista 32-bit

Your answer for number 2 was very helpful, but i am a little bit confused about what you mean for the first 1

Hmm… You did not mention which tutorial… So i assumed something, where sculpting is used… And that usually implies applying Multiresolution modifier to the initial mesh… nm, guess that wasn’t appropriate here.
‘My human head’ - then it’s what - background image?

in the regular subdivions modifier enable the vertex and or mesh options … :