I believe the exit pages are recorded. But the exit pages are not in the bounce or time on page calculations. That's for ga.
Now one minute on the important pages means the visitors did spend some time looking at the content. What's the content's length on these pages, I mean whats your expectations how long they should stay on the same page? Also what's the next page target? Is it the shopping cart, a checkout page? And see the bounce rates of the shopping cart or checkout pages. You should expect very low bounce rates on these.
Then check the page loading speeds. Are the pages loading fast enough? You could use some anonymous proxies from different geolocations, if you target different countries, for testing purposes, see if there are latencies. GWT displays the times the bot takes to parse pages, check the average and check for load spikes if there're any. Analytics also has similar figures. Are there any latencies recorded?