In terms of your friend's lab puppy, I would definitely let them play together when they are young. Observe them closely so that you know how they play. It is extremely unlikely that your friend's lab will go into heat before 6 months. 8 months or later would be more typical. If your friend is not planning to spay her girl before then, she should be on the lookout for any swelling of the vulva or bleeding. Typically bitches bleed 3 weeks, and they are fertile for only 4 or 5 days in the middle of that 3 week period. You and your friend should, of course, keep the dogs apart during the entire period when the bitch is bleeding. Occasionally, bitches have "silent heats" where they do not bleed, or perhaps your friend is not very observant. So you can't be 100% sure that she is safe.
Another sign to look for is any interest on the part of your poodle that seems different from their normal play. You will get to know what their normal play looks like. Breeders sometimes know when their bitch is fertile by observing the reaction of their stud dogs. Look for any behavior that looks more sexual than usual -- sniffing the girl's butt, whispering sweet nothings into her ears, and of course any attempts to mount. If your eyes are open, you should notice what is happening and keep the two dogs apart whenever you observe any of the above signs.
Thank you for all of the very specific information! Appreciate it!