GP's aren't hard, if you have the tools. Swivels, extensions, sockets a haynes/chilton manual, etc.
Breaking off usually only applies to Autolites(autoswells). I had 2 of those in my truck when I did mine, and had no problems getting them out, so I got lucky I guess.

I had a similar problem on my exGF's ford freestyle van. A couple of her spark plugs broke off, but luckily the bolt portion was still there to remove them. If you think doing a this job is hard, do it on a sideways engine, with big hands, a tiny space, and underneath the vehicle. There is a reason why the Ford dealership wanted 300$ to do all of her spark plugs! Glow plugs were like changing the ONE spark plug on my quad compared to that van... Moving on.

How many miles are on the truck? Did the PO say anything about the maintenance he did to it? If not, are you able to contact him and find out?

There are probably about 10 pages of GP removal threads if you do a forum search for them. Right next for forum tools, is a search forum option. Type in your query and hit enter, that simple!

A lot of them come complete with pictures and step by step techniques etc. I can't comment on the buzzing. My truck seems to have been de-buzzed.

 

It has 87213 miles but a lot of idle time it was a town truck and ambulance as for the glow plugs I had a shop ohm them out and told me one or two worked and that the left valve cover would be hard to remove may have to take the motor mount off and jack the motor to make room forgot what was in the way heater box or something so been putting that one off guess the time may have come to do the job but I got other things first need tires just did brake line and need to do more of them truck came from up north and the salt is eating her up thats the second one I put on so Ill change the rest don,t like hitting the brake to find out nothing is their. the good old emergency brake worked though so I will try a few more thing for the starting and hope for the best its not a every day driver but it is a work truck that I need thank you for all your help. And Happy New Year to You All

 

The passenger side valve cover can be tricky, only thing required to be removed is that black box held by the 5/16 screws. Otherwise you can use a ratchet wrench to get at all the bolts but using my cordless impact and extensions/universals 13mm(I think) go to town and you can have valve covers off in minutes

 

Just a reminder as well last week my stater relay went out, its located on the passenger fender near the battery.
I was not getting any communication with the PCM just like you but it sounds like yours is glow plug related its an easy task, there is a couple great write ups. I picked up motorcraft plugs at o reilys for 90$ ZD-11 are what you want.

 

Is it an ambulance with the van front end? If so then the getting the valve covers off would be more difficult, but if it is a truck front end, then doing the glow plugs is not a bad job at all. REPLACE THE GLOW PLUG RELAY and that should stop the buzzing and no WTS light/no start issue. At least then you can plug it in and start it until you can get the glow plugs changed.