Why even split each location into its own campaign if search volume is so low? If the client wants to dominate all areas as much a possible, it sounds like you wouldn't have budgetary reasons to warrant a split. I think you are over complicating this. Put everything in one campaign unless you have an actual reason it split it up. You can group services and cities by ad group.

Having one campaign will give you more bid strategy options. You may not have enough conversion volume in some campaigns if search volume is an issue. Google recommends to consolidate as much as possible.

If you broaden your keyword set, you'll be eligible for more searches. It's only logical that your impression share drops when there's a lot more impressions available. Don't worry, this is normal. Keep an eye on your search term reports to make sure that you're not catching worse quality searches than before.

The best ad schedule and device bid adjustment is the one based on data not on opinions. Nobody here can give you the answer. You have to look at the account history and see how devices have historically performed. Similarly, check performance during times of the day and days of the week. Download the pe4foance report and pivot it and you should be able to see.

If the campaigns are on bid strategy other than Max Clicks or Target Search Impr. Share, you don't need to do anything. Google knows when and where to show your ads. It will ignore your bid adjustments unless you want to completely exclude some devices.