Additional thoughts for you:
1. Have you considered what server to use? Your J2EE project will not run without a server you know.
2. Are you considering buying for proprietary software to run this thing(database, libraries) or are you planning to go the freeware way?
3. I'm sure there'll be some reports generation that will happen on your system. Have you decided what reports library to use?
4. Last of all, I'm just throwing this out there, but look into using frameworks like Spring and Hibernate. You can add this to your experience.

Good luck!

Since I'm not quite convinced 10^6 elements should be creating a seg fault, I'm going to assume that (1) you're using Visual C++ which has a default stack size of 1MB or (2) you've got a programming error. You're using conio.h, so I know you're on a Windows machine. As a workaround you can create the array on the heap. As good practice, you shouldn't create large objects on the stack.

For a sort algorithm you could give it a million-entry array of random numbers and have it sort the array, then run through the resulting array and ensure that all elements are greater than or equal to the previous element. That will allow you to check the array was properly sorted in linear time. Then you could put this all in a loop and time it (using time, or another library -- likely OS-dependent) then take the average of say 100 or 1000 million-item arrays being sorted and/ or checked to see about how long it takes to sort your arrays.