How to put values on boxplot and control its width?
X<-c(1,2,,3,4,4,5,5,6,6,6,6,6,7)
I need to write values for min, max, 1st quartile,
You can use horizontal = TRUE get a horizontal boxplot and axes = FALSE to remove the axes. staplewex = 1 sets the staple width the same as the box width
Then you can use fivenum to return the statistics used to create the boxplot and use these as text labels, fiddling with the y value until you have what you want
boxplot(X, horizontal = TRUE, axes = FALSE, staplewex = 1)
text(x=fivenum(X), labels =fivenum(X), y=1.25)

Note that i've inserted a 3 for the value missing in your example data X