sleep(1); #waits/sleeps for one second then continue running the script
Q1. How to make this 1/100 of a second? which of these work: 0,01 or 0.01 or .01 ?
None of the above!
usleep is what you want for fractions of a second.
usleep(100000) will sleep for one tenth of one second.
Your other options are
time_nanosleep which takes both seconds and freaking nanoseconds (one billion of which are one second), and
time_sleep_until, which will sleep until a particular unix timestamp has been reached.
Be aware that your system might not have millisecond resolution, no less nanosecond resolution. You might have trouble sleeping for precisely tiny, tiny amounts of time.