You're so funny!! Yes, just call him- don't worry about whether you get through to him or leave a voicemail- the point is to get to ask him if you can meet so either way will be fine! Saying you want to meet for lunch is fine- then he won't expect you to be staying for the evening. You could also say that you need to head back for the evening if you're really worried about that.
Also don't worry about discussing your career plans with him! He'll be flattered that you want his advice, and I'm pretty sure he won't see it as pressure/make him nervous. Is he the kind of guy who gets easily nervous or stressed at the thought of giving musical advice? If you've made it clear that you want advice on your career and aren't planning to ambush him into saying whether he wants to live together I'm sure you'll be fine!!
