Yes, Frontend Mentor offers both free and premium challenges. You can access many projects for free, and you can choose to upgrade for more advanced challenges and additional features.

Yes, you are encouraged to use Frontend Mentor projects in your portfolio. It's a great way to showcase your coding skills and demonstrate your ability to implement designs.

If you're stuck, you can ask questions and get support from the Frontend Mentor community on their Discord server or in the solution discussion sections. It’s a helpful and active environment for learning.