Well...you certainly won't damage the Pi by using "too much memory" or running too many programs. Things will just get slower, for a variety of reasons. One consideration here is which version of the Pi2B you have as the SoC was changed between the Pi2Bv1.1 and the Pi2Bv1.2, with the later being about 30% faster even with the same (900MHz) clock speed.
However, either version of Pi2B has 4 CPU cores, so--at least on a theoretical level--each of the processes you want to run plus the OS could be running in separate cores. The OS will take care of memory, allocating it as needed. That said, if you try to use more memory than is available, the OS will swap blocks of memory out to the SD card, and that is where problems are likely to occur. Each cell of an SD card has a limited number of time it can be written. The (very small) processor in the SD card tries to even out the wear on the cells, and that takes overhead (it's also the major reason why you can corrupt an SD card by just pulling the power).
There are command, such as "top" that will show you how much memory is being used and what the CPU load is. One thing you could do is run each application separately to see how the Pi handles it. Then start with one application and add the others, one by one, to see what happens.
If you find that you cannot reasonably run all the applications at once on your Pi2B, there ar e several solutions, depnding on what resource you are running short on. If it's CPU cycles, you can either split the applications across more than one Pi or you can upgrade your Pi2B to a Pi3B or Pi3B+. If you're running out of memory, you can try setting configuration data for the applications to reduce the memory footprint or--again--split the applications across more than one Pi. If you're only a little short on memory, look carefully at your system configuration to see if you can change the memory split between the CPUs and the GPU.
Welcome to the wonderful world of performance tuning. You get to decide whether you want to throw time and energy at any problems you have, or whether you'd rather solve them with money in the form of more Pis. At least Pis are inexpensive.