My goodness, a legal question with enough information to provide a meaningful answer - well done! You should not rely on the following, as I am not an attorney, but my unqualified opinion is:

Yes, it's a problem. Clause 5 means you are giving company X ownership of anything you think up in any context during your employment and for 6 months afterwards. As well as the examples described below, that could extend to things someone else does to which Company X argues you made a contribution - you tell me about your favorite way to eat peanuts at a conference in the company of another Company X employee, I launch a new snack food 3 months later, Company X claims you made a contribution and as your implicit assignee, sues me for the value of your input. In short, you must assume you have no creative life of your own during employment.

Now, the reference to the California Labor Code refers to a piece of law (http://www.leginfo.ca.gov/cgi-bin/displaycode?section=lab...) that says inventions which have nothing to do with your work can't be controlled by your employer, and clauses in employment contracts attempting to exert such control are void. This should get you off the hook, because under California law just about anything you create is an 'invention'. But that might first entail an expensive argument over whether your non-work stuff qualifies, the degree to which it was truly and fully independent of your work, and (given that it's a consulting company) whether it might overlap with any of their clients' business operations.

So you have a conversation with a Company X employee about his job consulting for Hotel Chain Y. Later you make a slight improvement to Napkinboard. But Napkinboard lets people rate dining halls, hotels have restaurants, and a restaurant is like a dining hall...

Clause 6. requires you to list everything you might possibly need to identify as your own creation before starting work; in other words, your current intellectual property assets. I would consult a lawyer for this too. Sure, the practical purpose is just to fence off your Napkinboard project, but is that your sole creative work in existence? I mean, what about your copyright in this 'Ask HN' post - especially as it may reveal something about the operational methods and policies of Company X? It's their attorneys' job to think in such broad terms if a dispute arises in future, so you should too.

Is that all of clause 6, or did you just cut it off there? If the former, it seems like a bare-minimum acknowledgment of what's yours, compared with the very comprehensive scope of what's theirs...and chances are that your haven't formally registered any of your copyrights or designs, so the onus would be on you to prove what does or doesn't qualify.

Re. the ethics code, I'd want some written acknowledgment of your rights in and permission to continue working on your Napkinboard project. If a request for this is brushed off with 'it's a standard contract' you can politely say 'great, I'll just run it past my attorney then and shot it right back to you.' Obviously you don't want to get into a protracted negotiation that would impede your ability to take the job, but nor do you want to hand them your ass in a sling. 'Standard contracts' are written to serve the needs of the party who offers them, not to be equitable to both parties.

Remember, I'm not an attorney!