The benefit of following your client’s navigation is that it makes your job easier. By that I mean it is easier to get good quality scores because the keywords are already mapped to a landing page with relevant copy.
The current structure is fine, but make sure each keyword is mapped to a landing page with relevant copy — Mention it in headings, graphics, text, alt-text, captions, etc.

SEM Rush or Google keyword planner are great tools to find the high and low-range bids for your keywords.
As far as formulas go, I would take the high and low ranges for all of a campaign’s keywords and create an average CPC range (the average of all low range estimates through the average of all high range estimates), then use the median CPC (split it down the middle) for your starting point.
Make sure this target CPC isn’t more than your daily budget. If you’re dealing with low budgets and highly competitive keywords with CPCs around $50/click, you won’t see much volume at all.
Besides that, you can also find your ideal max CPC by figuring out your click or conversion per day goals. If you need X amount of clicks per day to see a conversion, take your budget and divide it by that many clicks to get your max CPC.

Raise your quality score, add budget to the campaign, and once you have enough data in the campaign, use the maximize conversions bid strategy at a target CPA you are comfortable with.
Once you let the algorithm take control of the bidding you don’t have to worry if the expensive clicks are actually worth it. This is because Google’s AI decides who is worth the high bid. This takes the risk out of setting a blanket bid for all users manually (not to mention saving the time it takes to make manual adjustments).

Remember that it’s about quality, not quantity. You want to make sure that rhigh intent, specific keywords are treated carefully. You don’t get a lot of opportunities to convert the perfect niche user! I wouldn’t dilute your longtail ad groups with broad keywords.
What you can do to boost clicks here is use a maximize clicks bid strategy and leave the cost cap off of it. I do this when I have specific, low-volume keywords I want to get as much as I can out of.

Usually if you’re under 95-plus percent you’ve got room to grow. Add budget, or change your bid strategy to maximize clicks or target an impression share to increase this. We don’t have specific benchmarks because it’s very dependent on context.
As for rankings, you want to be in the top four ads as much as possible so the benchmark there is closer to 85%. It’s possible with extensions, high quality scores, and tightly targeted ads.

I would say if you see a new search term that is killing it, add it to a new ad group as often as you are optimizing, just don’t force new keywords in because you feel like you have to. You don’t want so many keywords in an adgroup or campaign that your budget would never be able to cover all of them. Take a look at you CPCs, take a look at how much daily budget you have, then look at how many keywords you have. Does it make sense to have 50 keywords at an average CPC of $15 for a $30/day budget? No.
Another point against too many keywords is that often times root keywords are enough to trigger your ads for more specific keywords, especially in automated targeting. Much of the time, you have overlapping keywords that just make optimizing more difficult. The keyword “Property Management Software” should cover search terms like “best property management software” or “property management software for small landlords”, for example.
You could have a specific ad group for longtail search terms that covert as you find them if you want to be extremely efficient, but then you might run into the longtail problem we addressed earlier. Sometimes less is actually more (efficient).

I would take a look at the search terms reports and make sure your ads are triggering for the right users. Sometimes there is a disconnect between the keywords, copy, and landing page and you need to re-think the first two pieces of the puzzle.
What kind of person are you trying to bring to the landing page? What are they expecting to see? Did you tell them to take action in your copy? Prime your prospects to take a specific action in the ads and, if possible, the keywords themselves. Try long-tail keywords with verbs like “How to find property management software” or “sign up for property management software”.

Enhanced! You’re really limiting yourself without enhanced CPC, this can help you win more auctions at a reasonable price and help you gather conversion data faster.

I tend to either use multiple match types for the same keyword or use one match type for multiple keywords within a single ad group. In your case, for this specific client, I would probably use multiple match types for the same keyword and put multiple keywords in the same ad group as long as you stick to the theme. Keep the keywords to a minimum so you can more easily optimize.
As a side note, exact match is less exact than it used to be while phrase match is more versatile than it used to be. If I had it my way I’d stick to the themed structure and just use phrase match across the board. But if your client is insistent on the use of exact match, try to create phrase match ad groups or campaigns then show them results from phrase match ad groups. I guarantee they will be better and get you the performance data you need faster.

Increasing your ad rank by improving quality scores and using automated bidding (or at the very least enhanced CPC). Google gives each ad vying to win an auction a literal rank to decide who’s ad to show, so in order to increase your impression share you need to raise your rank. Make sure your ads match your landing pages as closely as possible and that you are letting google’s algorithm decide when to bid and how much to bid as soon as you have enough conversion data. Budget is a major lever for ad rank but so are the other things I mentioned.

I haven’t found this metric to be useful outside of gauging quality scores, but with a sample size so small (1 click = a 16% CTR) It’s hard to tell if your CTR will actually be much higher than they think it will be. Do what you can to boost impressions and get more data before deciding if you have a CTR problem.
Overall, I don’t think you need to look too thoroughly at this metric, you’ll know if your CTR is actually in trouble soon enough!