There sound like a couple of different issues going on here. Let's sort them out.
Regarding the repairs done over the past 20 years, that's not too unusual, and the advice from the home inspector is pretty typical, and OK. Especially on very expensive or life-threatening issues (for instance, plumbing and wiring), I'd like to call in an expert. Same if it were something like foundation work. Home inspectors range from terrible to great, but even the best tend to be strong in some areas and not so strong in others. So, yes, you have every right to get your own experts in there.
I don't understand why everyone's feathers got ruffled when your friend brought in a local contractor friend. That makes perfect sense to me. (Again, I'd probably also want an expert in any particular field I was concerned about, but if I had a contractor friend I'd absolutely ask for his help.) Maybe your friend's agent or the seller's agent thought your friend was just using this as a ruse to get out of the contract. I don't know, but that's the only thing I can think of.
You say he's felt forced to shop for his own mortgage. On the one hand, he's got every right to do that; it's his mortgage; he's the one responsible for paying it. On the other hand, his agent should have provided leads and suggestions and should have assisted in every way. That'd be to make sure that your friend was dealing with someone who could actually get the deal done, professionally and on time. In fact, Realtors often get very nervous when a buyer insists on using a broker or lender they've never heard of; that can mess up an otherwise smooth transaction. So, it's in the agent's best interest to assist the buyer in obtaining financing.
You say the process isn't going fast enough for "the double trouble agents." The contract calls for certain steps to occur at certain points--buyer to apply for a loan within x days of a ratified contract, that sort of thing. If he's in compliance with that, there shouldn't be a problem. In fact, agents usually stay on top of the process (but not being "double trouble") just to make sure that the right steps are taken in the right order.
There appears to be some miscommunication between your friend and the agent. It sounds as if he feels that he's been left to "twist slowly in the wind" and abandoned by the agents. On the other hand, it sounds as if the agents (or at least his agent) feel that he's somehow gone off on his own. I'd suggest that he schedule a meeting with his agent as soon as possible...a face to face meeting to try to get back on the same wavelength. If that can't be accomplished immediately (and you say the agents seem to be MIA), your friend might call the agency's managing broker and explain the problem to him/her.
Hope that helps.