1. We need to remember that Odin sacrificed one of his eyes to gain incredible knowledge and wisdom. To that end, he has over time put MANY plans in motion to try his hardest to circumvent, get around, bypass, trick, dodge, or evade Ragnarok, all to no avail. How many of those plans centered around Thor? Several. He's like any dad, he wants to see his boy succeed. However, Thor doesn't have the vast wisdom and knowledge of his father, so Odin tries to teach him to use his head more.
2. You said a few comments back that Thor became legendary but why hasn't Orion? Well, not to be rude, but Thor's been around for centuries in our real life Lore, and Orion was just invented several years back. Give Orion time and who knows, the right writers and enough of a fan base can make anyone legendary.
Mjolnir is part of Thor's basic character concept, but there is no single set of rules as to how the hammer should be used, how its powers are related to Thor's, or what the worthiness enchantment means. Nor should there be. It is open to each writer's interpretation and the hammer can be used in a variety of different ways.
I think some ways work better than others, as I'm sure is the case for all fans. But, as with a lot of material in comic books, there hasn't been much consistency over the years.
The key phrase, though, is "Whosoever holds this hammer, if he be worthy, shall possess the power of Thor." Whether the power resides in the hammer, or in Thor himself, or some combination of the two, it is Thor's power. What exactly that means and how exactly that works is open to interpretation.