I would say that it is possible to begin with a large game, but only if you are very sure that you can handle it. Seeing how you are already not too motivated to devote large chunks of time to writing, it may be easier to start with a game where the sole focus is on the story rather than adding in extra complications like variables and items.
If you do want to implement a health system in the future, the usual way is to use variables (I think another member put a link for that earlier) and set it to how much health you want the reader to start with. Then under each link that causes damage to the reader's health, you can deduct some variable points. There's a setting in the variables part that allows you to bring the reader to a specific page once health falls below a certain number (I usually set it to 0).
As for the dream powers in Dreamtruder, they are items that can be found on certain pages and a lot of the links were item restricted so the dream powers could unlock different options. Besides that, you should also learn how to use items to find out how to do that. I recommend reading some articles in the Help and Info section to get a better understanding of how to use the site.
