My first recommendation is to find the audience you want to help FIRST, not an overlying topic. I think people go about help websites backwards and think of a topic first, write content about it, and hope that someone reads it.
So who can you help? What type of person would you be able to give advice to?
For example, let's look at your Weight Loss topic...
- Are you helping elderly people? young people? Teenagers? Adults?
- Was there a certain kind of health condition that made it hard for you to lose weight, and is this a relatively common condition?
- What struggles did you go through, and is this type of struggle common?
- Were there any products that helped you lose weight?
- Is your story unique, and can you create a helpful ebook about it to sell?
- What was your exercise regime like (if you exercised), and are there any equipment that you can recommend (weights, jump ropes, exercise balls, etc.)
As for your second question...
What do you mean by "normal navigation like a website"? Navigation links at the top, you mean?
You can definitely run your Wordpress like a static website. That's what makes Wordpress so awesome My website is on the Wordpress platform, but I run it like a static website. I just moved my blog to another page. You can even get rid of the whole blog feature if you want.