Oh wow, so much. Before going further you should take the time to go through the tutorials provided in help. Pay attention to how their styles are set up.
First your text style (new grading) is set to be sized, for C3d text scaling is handle by the label styles.
Second all your label styles are set to plot letters 2" and 3" tall, these values should be in the .06" to .25" being the final plotted height of the text.
Third your model space scale has nothing to do with the final plotting and can be changed to anything convenient for the current task you are performing or to match the scale of the view port you are currently setting up.
Fourth your viewports should have both annotation scale and standard scale set to the same scale, that being the final plotted scale. If you plan is be at 1"=50' (or 1:50) those scales should be 1"=50'. The viewpport controls the final scaling when plotting.
fifth when plotting from paper space your plot scale should be 1"=1' (1:1) as scaling is handles by the viewports and your paper size should match the size of paper you are plotting to, generally 24"x36" in the USA.
Sixth you should set lts, pslts and mslts to 1 (linetype scale, paper space linetype scale and model space linetype scale) the your linetypes generation will match the current scale in which ever space you are in. In general all objects should have their linetype scale of 1 also.
I could go on but I hope this would give you the idea of how things should be.
To illustrate the function I described, I modified your styles (fast and without much attention to final appearance) setting text heights and offsets to .1". I created two layouts for 24"x 36" paper, with your original border scaled to approximately 24x36. The first layout has 2 profile views and 2 plan views scaled at 1:50 and 1:30 to illustrate how the view ports control scaling. The second layout is a portion of your section layout at 1:10. Note that all of these viewports are of the same model space with a the scale set at 1" = 10', text size and line type scaling based on the viewport scale.
Hope this helps ;).