If you're entirely stumped it's not a bad idea actually to unlock the solution. However, make sure you take the time to analyze the solutions of other users until you understand what you were getting stuck on. Once you feel like you have a solid understanding of what you were missing, attempt to solve the kata again (even without the reward incentive) without having to look back at the solutions. Otherwise, there's not much benefit to unlocking them. If you're concerned about losing out on potential honor, there's over 5k challenges on the website, so it's not really a big deal if you can't get points for a few of the harder ones.

Remember to utilize the language's documentation and other resources if you get stuck before unlocking the solution though. Often times what I'll do is bookmark the challenge I'm stuck on, and spend some time doing research on it. If it still doesn't come to me, I'll bookmark the kata and attempt to solve it later, usually I come back at it later with some new ideas. In most cases, this works out for me. But, I've had to unlock solutions a few times, especially when I first started the 4kyu+ optimization challenges.

Rote learning is always dangerous because it often leads to "going through the motion" scenario.
You see but do not perceive.
If you do not have photographic memory, I suggest that you repeat the exercises few weeks later after your memory of the respective solutions fade away.

The way I see it is that as long as you learn from doing so, then that's all that really matters. I've done it myself once but made sure I fully understood it, made notes and reflected on it before I moved on.

No, but you should spend time studying other users solutions.

Write in that kata's discussion, not here. And mark your post as having spoiler content there (can't be done here).

True and truthy are not the same. Idem for false and falsy.