The idea of moving in the 4th dimension certainly creates interesting possibilities. Sure, a being capable of seeing in 4d can see both the outside and inside of a 3d object at once, given it fits into his/her visual scope. A 4d being can, however, not walk through 3d walls (only 'over'), but his/her 3d shadow (or rather projection) will seem to perform this wonderfull feat. If the 'light source' causing the projection can be moved, then the 3d projection can even appear to fly.
But, if you believe that the above possibilities are real, then you have not discovered the truth about science yet. The rest of this post might help you on your path.
A 0-dimensional space can not be seen by us because it is infinitely small and has a zero measurement in all dimensions. A 1-dimensional space (commonly referred to as a line) can also not be seen by us, because, although it has a measurement in 1 dimension, it is infinitely thin. A 2-dimensional space (flat surface) can not be seen because it is infinitely thin. I assume that a 4d person will not be able to observe a 3d space, because it is infinitely 'thin'. These facts should make you wonder a little. But, let me continue...
You might believe that 3d space is described by 3 mutually orthogonal axes (directions). But, in fact, 3d space can be described by an infinite number of arrangements of axes, as long as there are 3 of them and they are at angles greater than zero with respect to each other and they intersect. The same holds for 2d space (and, of course, 4d space).
Now, to rock your foudations:
Our universe is not 3 dimensional. Our universe is only described by a 3 dimensional coordinate system. The reality: there is no 4th spatial dimension. Dimensions are only units of measurement. We require 3 measurements of length to describe a position in our universe (we also need a reference position, of course). Measurements of time, temperature, etc. are also dimensions. All along you have stared yourself blind at vocabulary.
This brings me to the true nature of science, something you should never forget:
Science does not tell us what our universe is, but rather, it tells us how our universe functions. Science uses the language of mathematics to describe the universe, and the notion of spatial dimensions is just another mathematical tool.
I'm not saying that 'hyper space' wormholes (which would allow us to use the shortest possible path in 'hyper space' to travel between two 3d coordinates) does not exist, or cannot be created. What I am saying, is that we only use mathematics to describe the mechanics of the wormhole, not what or where the wormhole is. If, indeed, our mathematical tools can describe reality closely enough, then maybe we might be able to someday create those funky wormholes.
I have to admit, that I came to this forum looking for ideas of what would be possible in 4d space. But, as I carefully thought it through, I came back to the truth of science, and as I remembered it, everything suddenly made sense again.
So, remember that a 2d space (flat surface) is not a physical thing. It is only a mathematical description of the face of a piece of paper. Also remember, that we, as '3d' beings, can not see in 3d. What we see, is a stereoscopic image (providing the sense of depth) built up from two 2d projections of the world onto our eyes.
I hope my words could bring you some enlightenment, and may you always practice science truthfully. :-)