Not much you can do except try to ensure that the land is graded away from the house, the gutters don't drain next to the foundation, and you sump pump doesn't fail. You can build the walls so the only place water can come in is via the sump, but you probably can't close it off successfully. Think of the basement as a boat...there has to be an outlet or it will try to float. The sump gives it a low pressure place to come in rather than pushing through the next weakest place. Moving the sump pump up probably won't make any difference about the amount of running time it gets. In my unprofessional opinion, I'd rather have it maybe 6" off the bottom of the pit so that when it does run, it runs a bunch out, rather than turning on for much shorter time and far more often. If the grading is good, and the gutters are run away from the foundation, and you have significant water...it is ground water...not much you can do about it. The house I grew up in was about a 1/2 mile from the towns spring fed water supply. During maybe half of the year, if the power went out, we could get up to a foot of water in the basement. You may want to look into a battery backed up pump for that possibility.