Combine lattice xyplot and histogram - r

Question

Could someone help me please to upgrade my plot?
a) In the plot, there should be print only one y-scale per row.
b) To print a more comfortable legend, that means
1) change the order of symbols and description,
2) print line in the same x-position like superpose.symbols,
3) and print symbols for the histogram.
d1 <- data.frame(x=c(NA, 13:20, NA), y = 25, z = c(rep('march', 5),
rep("april", 5)), color = c(c(rep(c("red", "green"), 2), "red"),
c(rep(c("blue", "yellow"), 2), "blue")), stringsAsFactors = FALSE)
d2 <- data.frame(x=c(NA, 20:27, NA), y = 23, z = c(rep('may', 5),
rep("june", 5)), color = c(c(rep(c("blue", "red"), 2), "red"),
c(rep(c("blue", "yellow"), 2), "blue")), stringsAsFactors = FALSE)
d1<-rbind(d1,d2)
sup.sym <- trellis.par.get("superpose.symbol")
sup.sym$alpha<-c(1, 0, 0, 0, 0, 0, 0)
sup.sym$col<-c(1,2,3,4,5,6,7)
sup.lin <- trellis.par.get("superpose.line")
sup.lin$col<-c(1,2,7,5,5,6,7)
sup.lin$alpha<-c(0, 1, 1, 1, 0, 0, 0)
settings<-list(superpose.symbol = sup.sym,superpose.line = sup.lin)
xyplot(y ~ x | factor(z), data = d1
,ylim = list( c(22, 26),c(22, 26), c(0, 1),c(0, 1) )
,layout=c(2,2)
,scales = list(y = list( relation = "free" ))
,par.settings = settings
,auto.key = list(text = c("A","B","C", "D")
,space = "right"
,lines = TRUE
)
,panel = function(x, y, subscripts) {
if(panel.number()>2){
panel.histogram(x,breaks=3)
}else{
panel.xyplot(x = x, y = y,
subscripts=subscripts,
col = d1[subscripts, "color"])
}
})