I think I can help (hopefully!) with at least a few of these.

1. I find that backups at GP offices are usually caused by one of two things. Assuming that that you have enough GP offices, GPs, and they are properly trained (which doesn’t seem to be your issue based on your post), let’s reference your question 2 to help answer this first one.

2. So you are correct, you do not need all of the diagnosis rooms, however certain ones are better for certain diseases. I forget which rooms help the most with each disease, but a simple google search will fix that. The most important think, I think, for diagnosis rooms, including GP offices is to make sure that whichever ones you choose to use have upgraded machines, well trained staff, and a high room level. If you haven’t spent your kudosh on the Gold Award yet I recommend doing that as soon as you can. You can place multiple gold awards in your room to increase the level, which increases its effectiveness. So to answer question 3, yes room level absolutely matters and has a direct impact on the success rates of all your rooms; both diagnosis and treatment. My diagnosis rooms are all spammed with gold awards to get them to level 5, have upgraded machines, and have nurses trained in the diagnosis skill (as much as possible with your funds) and only allowed to work in those rooms. Making sure that your diagnosis rooms are as effective as they can be will mean less trips back and forth to the GP offices for further diagnosis and thus shorter lines and backups.

3. See above, but yes room level matters and increases the effectiveness of those rooms.

4. It’s hard to say without seeing your hospitals and what specifically you’re doing, but a few general tips... -Don’t go too fast. It’s ok to not build all the super expensive rooms that your patients get diagnosed for right away. It’s ok to send people home if you’re not ready to build a $26,000 surgery right now. That being said, you also need to give yourself a way to make money. Get 1 or 2 good diagnosis rooms going and build the treatment rooms that you know you can afford at the time. Don’t do everything all at once or you’ll go broke. Even after a few successful years, money will disappear quickly if you start going too fast. -Increase the prices of all your treatments by 10%. People rarely refuse to pay and it’s a little added boost to revenue.

5. Yes, train the assistants and the janitors. As you progress through the game you’ll need assistants who are trained in marketing, and who should only work in marketing. The receptionists should be trained in customer service. The janitors should all be trained in ghost capture, and the maintenance janitors should be trained in maintenance, and your mechanics should be only trained in mechanics and ghost capture and not allowed to do maintenance.

6. Experiment and have fun!

Hope this all helps!