Question 1 
I have a cube in which I have to represent the corner of the cube with some text. But I am finding difficulty in placing, I don't want It to be exactly on the corner, I just place in a similar fashion I have placed text for 1D plot and 2D plot, so that It should come aesthetically good. how to carry out this?  or is there any better way. 
Question 2
And I wanted to make a single plot which contains all three figures f[1],f[2],f[3]. Since the dimensions are the same It will create a problem.

    ClearAll["Global`*"];
    f[1] = Graphics[{Thickness[0.007], Black, Line[{{0, 0}, {1, 0}}], 
       Disk[{0, 0}, 0.05], 
       Text[Style[
         "\!\(\*SubscriptBox[\(\[Psi]\), \(1\)]\),(\!\(\*SubscriptBox[\(K\
    \), \(t, 1\)]\)\[Rule]0)", 15], {0, 0.1}], Disk[{1, 0}, 0.05], 
       Text[Style[
         "\!\(\*SubscriptBox[\(\[Psi]\), \(2\)]\),(\!\(\*SubscriptBox[\(K\
    \), \(t, 1\)]\)\[Rule]\[Infinity])", 15], {1, 0.1}]}]
    
    p[2] = Graphics[{Thickness[0.007], Black, Line[{{0, 0}, {1, 0}}], 
        Text[Style[
          "\!\(\*SubscriptBox[\(\[Psi]\), \
    \(1\)]\),(\!\(\*SubscriptBox[\(K\), \(t, \
    1\)]\)\[Rule]0,\!\(\*SubscriptBox[\(K\), \(t, 2\)]\)\[Rule]0)", 
          15], {0, -0.1}], Disk[{0, 0}, 0.05], Disk[{1, 0}, 0.05]}];
    p[3] = Graphics[{Thickness[0.007], Black, Line[{{0, 1}, {1, 1}}], 
        Disk[{1, 1}, 0.05], Disk[{1, 0}, 0.05], 
        Text[Style[
          "\!\(\*SubscriptBox[\(\[Psi]\), \
    \(2\)]\),(\!\(\*SubscriptBox[\(K\), \(t, \
    1\)]\)\[Rule]\[Infinity],\!\(\*SubscriptBox[\(K\), \(t, \
    2\)]\)\[Rule]0)", 15], {1, -0.1}]}];
    p[4] = Graphics[{Thickness[0.007], Black, Line[{{0, 0}, {0, 1}}], 
        Disk[{0, 1}, 0.05], Disk[{1, 0}, 0.05], 
        Text[Style[
          "\!\(\*SubscriptBox[\(\[Psi]\), \
    \(4\)]\),(\!\(\*SubscriptBox[\(K\), \(t, \
    1\)]\)\[Rule]\[Infinity],\!\(\*SubscriptBox[\(K\), \(t, 2\)]\)\[Rule]\
    \[Infinity])", 15], {1, 1.1}]}];
    p[5] = Graphics[{Thickness[0.007], Black, Line[{{1, 0}, {1, 1}}], 
        Disk[{1, 0}, 0.05], Disk[{1, 0}, 0.05], 
        Text[Style[
          "\!\(\*SubscriptBox[\(\[Psi]\), \
    \(3\)]\),(\!\(\*SubscriptBox[\(K\), \(t, \
    1\)]\)\[Rule]0,\!\(\*SubscriptBox[\(K\), \(t, \
    2\)]\)\[Rule]\[Infinity])", 15], {0, 1.1}]}];
    f[2] = Show[Table[p[i], {i, 2, 5}], PlotRange -> All]
    
    p[6] = Graphics3D[{Thickness[0.007], Black, 
        Line[{{0, 0, 0}, {1, 0, 0}}], Sphere[{0, 0, 0}, 0.05], 
        Sphere[{1, 0, 0}, 0.05], 
        Text[Style[
          "\!\(\*SubscriptBox[\(\[Psi]\), \
    \(1\)]\),(\!\(\*SubscriptBox[\(K\), \(t, \
    1\)]\)\[Rule]0,\!\(\*SubscriptBox[\(K\), \(t, \
    2\)]\)\[Rule]0,\!\(\*SubscriptBox[\(K\), \(t, 3\)]\)\[Rule]0)", 
          15], {0, 0.1, 0.1}]}];
    p[7] = Graphics3D[{Thickness[0.007], Black, 
        Line[{{1, 0, 0}, {1, 1, 0}}], Sphere[{1, 0, 0}, 0.05], 
        Sphere[{1, 1, 0}, 0.05]}];
    p[8] = Graphics3D[{Thickness[0.007], Black, 
        Line[{{0, 1, 0}, {1, 1, 0}}], Sphere[{0, 1, 0}, 0.05], 
        Sphere[{1, 1, 0}, 0.05]}];
    p[9] = Graphics3D[{Thickness[0.007], Black, 
        Line[{{0, 0, 0}, {0, 1, 0}}], Sphere[{0, 0, 0}, 0.05], 
        Sphere[{0, 1, 0}, 0.05]}];
    
    p[10] = Graphics3D[{Thickness[0.007], Black, 
        Line[{{0, 0, 1}, {1, 0, 1}}], Sphere[{0, 0, 1}, 0.05], 
        Sphere[{1, 0, 1}, 0.05]}];
    p[11] = Graphics3D[{Thickness[0.007], Black, 
        Line[{{1, 0, 1}, {1, 1, 1}}], Sphere[{1, 0, 1}, 0.05], 
        Sphere[{1, 1, 1}, 0.05]}];
    p[12] = Graphics3D[{Thickness[0.007], Black, 
        Line[{{0, 1, 1}, {1, 1, 1}}], Sphere[{0, 0, 1}, 0.05], 
        Sphere[{1, 1, 1}, 0.05]}];
    p[13] = Graphics3D[{Thickness[0.007], Black, 
        Line[{{0, 0, 1}, {0, 1, 1}}], Sphere[{0, 0, 1}, 0.05], 
        Sphere[{0, 1, 1}, 0.05]}];
    
    p[14] = Graphics3D[{Thickness[0.007], Black, 
        Line[{{0, 0, 0}, {0, 0, 1}}], Sphere[{0, 0, 0}, 0.05], 
        Sphere[{0, 0, 1}, 0.05]}];
    p[15] = Graphics3D[{Thickness[0.007], Black, 
        Line[{{1, 0, 0}, {1, 0, 1}}], Sphere[{1, 0, 0}, 0.05], 
        Sphere[{1, 0, 1}, 0.05]}];
    p[16] = Graphics3D[{Thickness[0.007], Black, 
        Line[{{1, 1, 0}, {1, 1, 1}}], Sphere[{1, 1, 0}, 0.05], 
        Sphere[{1, 1, 1}, 0.05]}];
    p[17] = Graphics3D[{Thickness[0.007], Black, 
        Line[{{0, 1, 0}, {0, 1, 1}}], Sphere[{0, 1, 0}, 0.05], 
        Sphere[{0, 1, 1}, 0.05]}];
    
    f[3] = Show[Table[p[i], {i, 6, 17}], PlotRange -> All, Boxed -> False]