If you call someone and tell them that you want to get a quote for evaluating what needs to be done and giving you a quote for the job, then he will either give you a number for the quoting the job, or tell you he will give you the quote, or may tell you that it costs $xyz but will take that off the price if you give him the job. You don't want a phone quote because that is useless. You want him to know that you want the quote to be itemized for different separable parts of the job so you can control the scope and cost of the work.
Don't expect him to completely disclose his work plan. He will be bidding on the result.
He will probably feel good about it because it looks like you are willing to pay for the cost of a quote and the value received. If you do it yourself or hire someone else he has no beef since he has been paid for his quote work.
If you consider yourself capable of doing the job yourself you should be able to determine whether the quote is what you are willing to pay to get someone else to do it.
If you want to get other quotes you can tell the other guys what you want done, based on the original quote, but I would not reveal the fact that you have a quote in hand. Those quotes may not cost anything since you are not asking for an assessment; you are asking them to bid to a spec. If you want to later ask the first guy for his best-and-final offer; or give him an offer for the original scope of work, you may do so.
You must remember the Golden Rule: He who has the gold makes the rules. You have the gold and someone else wants to get your gold. You make the rules and they must sense, without being bludgeoned, that you are making the rules.
You then have the option of hiring him for the work you want done, or doing it yourself, or give the job to anogther bidder. He may expect you to get more bids and if his price is too high I would probably offer him a price for the job. He may counter-offer with a higher price if he want the job and you should be prepared for that.
I would make it clear, after the contract is signed, that I wouldn't accept increases in cost unless they were agreed to in priced and signed change orders before he undertakes the task. You don't want any change-order $$surprises$$. The initial scope should be defined in a way that you will be satisfied with the job if you decline all change orders that the contractor may propose. If they discover that you are susceptible to change order up-sells you will have no end of them, and they will always be at a premium price.
The contract must have a schedule and progress payment terms that will not leave you in the hole if he defaults.
My experience is that the shortest contract (the least writing), that says only what the end-result will be, is the best contract for the customer. The only exception is where material affecting quality is specified. If he bids a Square D QO panel you should accept nothing less than a Sqaure D QO panel, even if he says something else is just as good or better. Avoid those nasty "for equal" phrases because he will substutute cheap stuff that he says is equal and you will be stuck with his junk.