Unles your programs are very big, the free package should assemble your project just fine.

And you can use the Simulator to see how your program operates.

If your programs are too large for the free version, ask.
I do not often use 8051, but others can probably point you to a free unlimited Simulator.

Yes. Simple programs are a lot easier in C. For example, there is aleady a standard library function:

int strncmp(char *string1, char *string2, int length);

And you would just say:

if (strncmp(buffer, password, 6) == 0) yippee....

David.