Three questions about two plots

Question

I used the following code

listPB1 = {{0.05, 0.0025}, {0.07, 0.024}, {0.09, 0.0915}, {0.11, 
    0.149}, {0.13, 0.199}, {0.15, 0.269}};
listPB2 = {{0.05, 0.0035}, {0.07, 0.026}, {0.09, 0.111}, {0.11, 
    0.1775}, {0.13, 0.236}, {0.15, 0.2915}};
listPfh1 = {{0.05, 0.00116}, {0.07, 0.002413}, {0.09, 
    0.003561}, {0.11, 0.00463}, {0.13, 0.005089}, {0.15, 0.008824}};
listPfh2 = {{0.05, 0.0005}, {0.07, 0.001}, {0.09, 0.0022}, {0.11, 
    0.004}, {0.13, 0.00454}, {0.15, 0.008}};

PB := ListLinePlot[{listPB1, listPB2}, 
   PlotLegends -> Placed[{"PB(FCFS)", "PB(SJFLHS)"}, {0.5, 0.9}], 
   PlotStyle -> {{Red, Thickness[0.004]}, {Blue, Thickness[0.004]}}, 
   FrameLabel -> {"New Calls Arrival Rate (Calls/Second)", 
     "Probability"}, 
   LabelStyle -> {FontFamily -> "Arial", FontSize -> 18}, 
   BaseStyle -> {FontFamily -> "Consolas", FontSize -> 15}, 
   FrameTicksStyle -> 
    Directive[FontFamily -> "Consolas", FontSize -> 18], 
   PlotMarkers -> {Automatic, 12}, Frame -> True, ImageSize -> 500];
Pfh := ListLinePlot[{listPfh1, listPfh2}, 
   PlotLegends -> Placed[{"Pfh(FCFS)", "Pfh(SJFLHS)"}, {0.5, 0.9}], 
   PlotStyle -> {{Red, Thickness[0.004]}, {Blue, Thickness[0.004]}}, 
   FrameLabel -> {"New Calls Arrival Rate (Calls/Second)", 
     "Probability"}, 
   LabelStyle -> {FontFamily -> "Arial", FontSize -> 18}, 
   BaseStyle -> {FontFamily -> "Consolas", FontSize -> 15}, 
   FrameTicksStyle -> 
    Directive[FontFamily -> "Consolas", FontSize -> 18], 
   PlotMarkers -> {Automatic, 12}, Frame -> True, ImageSize -> 500];

GraphicsRow[{PB, Pfh}]

and I got the result in the attached picture

I have three questions:

1. I want to add the letter "(a)" below the first chart and "(b)" below the second chart, and I don't want to add them manually using the Drawing tools inside Mathematica. Is GraphicsRow the best choice or I should use something else?
2. How to use the LegendLayout->Horizontal when the Legend has specific coordinates and not one of these (Top, Below, ...)
3. The chart in the first attached file shows correctly on Mathematica, however when I click select all and save as pdf, it will save like the second attached file. What could be the reason?

Answer 1

To place the label "(a)" below plot PB you can use:

Labeled[PB, "(a)", Bottom]

You can wrap "(a)" in a Style to control the size and face of the font, you can also wrap it in a Row to fine tune the position. For example:

Labeled[PB, 
 Row[{Spacer[5], Style["(a)", 18, Bold],Spacer[80]}],
Bottom]