Iím working through Poisson regression and am looking at the plots of the model that [R] gives. Crawley gives little guidance about the way the plots should look for Poisson regression. When itís linear regression I understand the plots. I donít think I can interpret the plots in the same manner (different assumptions).

My questions:

1) Of the 4 plots [R] gives which ones are actually important to look at?
2) What do these plots mean (see code below)?


Code: 
dat<-read.table("http://www.ats.ucla.edu/stat/R/dae/poisson_sim.csv", sep=",", header = TRUE) 
summary(dat)
dat$pcat <-factor(dat$prog, labels=c("General", "Academic", "Vocational"))
attach(dat)
b.<-relevel(pcat, "General")
m1<-glm(num_awards ~ b. + math, family="poisson", dat)
summary(m1)
par(mfrow=c(2,2));plot(m1);par(mfrow=c(1,1))
Thanks in advance.