That's correct, you will only get the code and the states of the bits & registers as they are at that time, If you download the program some internal bits will be in their last state, however, I/O will update that within one scan so if an Input is off then after I/O update it will be off from that point, however, latched internal bits may stay on if the logic that would reset it is not true.
Upload of a program to your PC will not affect a running process but just be aware that registers i.e. N7:xx will be forced to the value when you uploaded it, it will be set to the current value in the PLC if the code is true on scan so for an example:
Lets say you uploaded registers and N7:0 was 1234, then when you download the program it will be forced to that value, however, if the logic is such that it was writing continuously a value of 5678, then when the program runs that bit of code it will force the value back to 5678.