Your points are all valid. Yes, you should see where/how others in the neighborhood have their dishes setup. This gives some idea of workable locations. And of course, the owner has to be reasonable in their location requests.One thing I wont agrea on is telling the installer where " you think the dish should go and how to install the whole system " bluntly put its a fool that does this if they have never done this kind of work before and base the choices they make based solely on what they read on a website. To get an idea of what will work best you need to do alot of homework and not just on the web but by driving through diferent neighborhoods of diferent age to get an idea of where the dishes are mounted wether it be on a ranch or two story colonial or a Wright home.
When the installer gets there its time to talk to him and work with him or her on putting together and installation plan that works for you and him because you want the install to look good and most installers do to but you also dont want the guy to be there all day trying to jump through unrealistic hoops to satisfy dilusions of granduer and he doesnt want to be there either.
Ultimately, you should expect a fair honest answer from a good installer regarding a requested location. If that location just won't work, they should tell you why.
In my case, the location I requested was close to where every install in my neighbowhood appears to be done. My neighbors have theirs attached to the chimney. My installer said they don't attach to chimneys. Okay. How about next to it then on the roof? That was okay, and a better location than the one they originally suggested which was on top of the garage. The garage location was easier to get to, but the roof location was really no more difficult by any stretch. I climb it myself in checking the roof and putting up Christmas lights.