GNUPLOT: GPVAL_Y_MIN and GPVAL_Y_MAX in MULTIPLOT environment - plot

Question

This being my first question here makes me a litte nervous. Here I go.
What I want to achieve is to plot four different data files in a multiplot (2x2, maybe more). So far I succesfully plotted this disregarding the different ranges in the y-axis on each, the x-axis is, however, homogenous to all subplots.
So, what I would like is to set to each y-axis 10 "ytics" with a number of minor tics (and, by extension, the x-axis as well). I believe this is done with GPVAL_X (or GPVAL_DATA_X) and GPVAL_Y (or GPVAL_DATA_Y) _MIN/_MAX. So far so good.
This however, does not achieve the result I was aiming for: http://postimg.org/image/uyavbtxn5/
On panel A) the y-axis is correctly divided in 10 segments, not so the x-axis.
Panel B) display correctly both axes.
Panel C) Display the x-axis correctly, whereas the y-axis no.
Panel D) Similar to C), but on the y-axis the tics appear disordered.
This poses the following questions:
1) How can I produce correctly this multiplot using GPVAL (or GPVAL_DATA)?
2) Why the plotted function appears in front of the corresponding label if it specified to otherwise?
This figure was produced with the following code:
reset
# Term
GNUTERM = "x11"
## Output
set t epslatex standalone color solid size 20in,12in font "ptm, 20"
set o "test.tex"
# Axes & Labels
set style line 11 lc rgb '#2F4F4F' lt 1
set border 3 back ls 11
set tics nomirror out
set format y "\\tiny $%2.2t \\cdot 10^{%S}$"
set format x "\\tiny $%1.1t$"
set xlabel "$\\rho$"
unset ylabel
unset key
# Grid
set style line 12 lc rgb'#2F4F4F' lt 0 lw 1.5
set grid back ls 12
# Border
set border 31 linewidth .75 # thin border
# Multiplot Files
set multiplot layout 2,2 columnsfirst
## UL
## Labels
LABEL = "A) $sin(x)$"
set obj 10 rect fill at graph 0.3, graph 0.75 size char strlen(LABEL), char 2
set label 10 at graph 0.3, graph 0.75 LABEL front center
plot sin(x)
## Tics
set xtics add GPVAL_X_MIN,(GPVAL_X_MAX-GPVAL_X_MIN)/10.,GPVAL_X_MAX
set ytics add GPVAL_Y_MIN,(GPVAL_Y_MAX-GPVAL_Y_MIN)/10.,GPVAL_Y_MAX
set mxtics 5
set mytics 5
## LL
## Labels
LABEL = "B) $cos(x)$"
set obj 10 rect fill at graph 0.3, graph 0.75 size char strlen(LABEL), char 2
set label 10 at graph 0.3, graph 0.75 LABEL front center
plot cos(x)
## Tics
set xtics add GPVAL_X_MIN,(GPVAL_X_MAX-GPVAL_X_MIN)/10.,GPVAL_X_MAX
set ytics add GPVAL_Y_MIN,(GPVAL_Y_MAX-GPVAL_Y_MIN)/10.,GPVAL_Y_MAX
set mxtics 5
set mytics 5
## UR
## Labels
LABEL = "C) $cos(x) sin(x)$"
set obj 10 rect fill at graph 0.3, graph 0.75 size char strlen(LABEL), char 2
set label 10 at graph 0.3, graph 0.75 LABEL front center
plot cos(x)*sin(x)
## Tics
set xtics add GPVAL_X_MIN,(GPVAL_X_MAX-GPVAL_X_MIN)/10.,GPVAL_X_MAX
set ytics add GPVAL_Y_MIN,(GPVAL_Y_MAX-GPVAL_Y_MIN)/10.,GPVAL_Y_MAX
set mxtics 5
set mytics 5
## LR
## Labels
LABEL = "D) $cos(x) / sin(x)$"
set obj 10 rect fill at graph 0.3, graph 0.75 size char strlen(LABEL), char 2
set label 10 at graph 0.3, graph 0.75 LABEL front center
plot cos(x)/sin(x)
## Tics
set xtics add GPVAL_X_MIN,(GPVAL_X_MAX-GPVAL_X_MIN)/10.,GPVAL_X_MAX
set ytics add GPVAL_Y_MIN,(GPVAL_Y_MAX-GPVAL_Y_MIN)/10.,GPVAL_Y_MAX
set mxtics 5
set mytics 5
unset multiplot
# Clean-up
set o
set t x11
reset
exit 0