All variables are signed 16-bit ints, so their range is -32768 to 32767.
As for the maximum number of variables, the short answer is 32 to 48 depending on what else the program is doing.
The longer answer is that there isn’t a fixed limit on the number of variables, but you will run out of free memory if you create enough. If your program did nothing else, there is enough space on the stack memory for 64 variables. A typical program might need 16 free stack positions, hence 48 remaining.
Hope this helps,