I've never understood this kind of "option to buy" deal. For example, let's say we go through all 4 of your points. But let's say that Bayern have been impressed by his development, so they pay us 10 million to take him back there. So he ends up back at Bayern; we are 5 million richer, Bayern, 5 million poorer. Seems straightforward enough, but...
Right now, he's still a Bayern player. And (same as above), let's say that Bayern have been impressed by his development. What's to stop Bayern contacting his agent next week, and telling his agent that they'll pay Malik a 1 million bonus NOT to agree terms with Rangers? Malik accepts. So, he doesn't agree terms, we don't sign him, and he returns to Bayern. They are 1 million poorer (instead of 5 million), he's 1 million richer, and we are financially "neutral".
Or does the "deal" include an agreement that Bayern can't do that? (And if it does, honestly, I doubt that agents & clubs are averse to behind-the-scenes contact).