Is it possible to "hide" the New button on the Opp tab from certain users? If not, will a validation rule prevent them from opening an opp there yet allow it from the Contact record? Trying for all Opps to be opened from Contact to maintain Mktg Links
Right - turning off "Edit Access" would remove the ability for that profile to create or edit Opportunities. In reviewing your question, it's unclear to me whether that's what you were looking for - probably not.
One simple option would be to remove the Opportunity tab. You could replace it with a custom tab that implements just a Opportunity search or a report showing the user's opportunities.
I think this Help doc answers your original question, though it may affect the "New" button elsewhere in your application, too. I should have Googled it before firing from the hip.
You shouldn't rely on hiding buttons to stop users from doing things because users can still find the page if they type in the right URL.
One simple option would be to remove the Opportunity tab. You could replace it with a custom tab that implements just a Opportunity search or a report showing the user's opportunities.
I think this Help doc answers your original question, though it may affect the "New" button elsewhere in your application, too. I should have Googled it before firing from the hip.
https://help.salesforce.com/apex/HTViewHelpDoc?id=links_customize_override.htm