Last year at this time I was running 30 to 50 miles a week. for 3 miles i was usually getting around 18 to 20 mins, for 5 miles 35 to 40 mins, i never did an 8 mile run but for 11 miles i was usually getting around an hour and half. As for shoes for that 5 month training period i went throught 3 pairs of the same shoe, its also a good idea to have a back up pair for when they got wet and muddy. And even now i have a back up pair of the same shoe, you would be amaised out how much they get worn down just after a few weeks. also don't forget to have rest days, after i trained my ass off for months i ended up with a stress fracture and a desk job, Happy running