subplots of maps in R using hydroTSM package

Hello,
Please I need help with maps in R using the hydroTSM package.
I am doing some map work using this wonderful package but encountered a problem using "par".
My intention is to generate 4 plots and show them on same window as follows:


if (dev.cur() == 1) x11(width=14,height=8)
par(mfrow=c(4,4),mai = c(0.8, 0.6, 0.1, 0),oma=c(0,1.4,6,0.1))
 
library(hydroTSM)

############
## Loading the monthly time series of precipitation within the Ebro River basin.
data(EbroPPtsMonthly)

## Loading the gis data
data(EbroPPgis)

## Loading the shapefile with the subcatchments
data(EbroCatchmentsCHE)

## Projection for the Subcatchments file
# European Datum 50, Zone 30N
require(sp)
p4s <- CRS("+proj=utm +zone=30 +ellps=intl +units=m +no_defs")

## Selecting the first day of 'EbroPPtsMonthly' for all the stations.
# The first column of 'EbroPPtsMonthly' has the dates
x.ts <- as.numeric(EbroPPtsMonthly[1, 2:ncol(EbroPPtsMonthly)])

## Setting the name of the gauging stations
names(x.ts) <- colnames(EbroPPtsMonthly[1,2:ncol(EbroPPtsMonthly)])

##################################################
## 1) IDW interpolation and plot
## Probably you will need to resize your window 
## Not run: 
x.idw <- hydrokrige(x.ts= x.ts, x.gis=EbroPPgis, 
                    X="EAST_ED50", Y="NORTH_ED50", sname="ID", bname="CHE_BASIN_NAME",
                    type= "cells",
                    subcatchments= EbroCatchmentsCHE,
                    cell.size= 3000, 
                    ColorRamp= "Precipitation",
                    main= "IDW Precipitation on the Ebro")

## End(Not run)
 


However, the existing plot disappears everytime I run this code.

Question1: How can I run this code 4 times and show the 4 maps on 1 plot window as defined by 
par(mfrow=c(4,4))?

Question2: Is it possible to convert the X and Y axes values from UTM to lat and lon and show them on the map?

Many thanks for your insighful replies.

Zilefac.