The only time that copyrights can really get hairy is when it comes to working for profit. If you're doing something for your portfolio, sure, mention that you modeled it from a concept from wherever in the project description, but it shouldn't be too huge a deal. For example, if someone were to model my Medusa character using my concept sketch for it from my website, as long as they mentioned something like "Concept from www.mtmckinley.net," then I wouldn't care.

The only time I might care is if it is implied, or even outright said, that the idea was from the guy's head when it wasn't.

As for your star wars model, I really don't think that's a big deal. Lots of people model star wars robots and vehicles all the time... people are constantly spitting out fan flicks, etc.

Posting scans from a book like that, might be a tad more questionable, but I'd be surprised if there was anything that you couldn't find online somewhere.

My opinion.