I can confirm that you can apply any of their prepaid packs, most of which are far better than the one you quoted, I use 99GB full speed 30 days inc. calls, 319 baht + VAT.
I bought one of those several years ago and still use it. It can easily be extended past its initial 30 days. The only minor issue is the maximum validity you can extend to is 90 days - I did question them on this point and they just said that was the limit on their tourist SIM. Not an issue for me as I top up monthly in any case but if out of Thailand and not using it much you'll need to remember to top-up/extend every 90 days. And yes, it'll work in Germany, you can easily activate roaming through the Truemove app.
You can also get, and quite possibly you'll be asked for it, a 12 month statement from your bank. In case of Bangkok Bank you need to order that several days in advance, other banks can issue on the spot.
Visa exempt gives you a 60 days entry. You need to convert to the non-O with at least 15 days of those remaining. I'd be inclined to do it around 30 days.
The single non-O give you 90 days. The expectation is that you would apply for an annual extension in the last 30 or so of those. But if you want to leave and return in the preceding 60 days or so then yes you can get a re-entry permit.
You can apply for a single entry non-O e-visa in Italy. You can show the money in your Thai account to get that.
You do not need any insurance of any kind.
Arrive in Thailand and get a 90 day entry and at the end of that go for an annual extension. You will not need to show the money came from outside Thailand.
.Or otherwise you can arrive visa exempt and convert to the non-O in Thailand.
There have been many posts about e-visas being issued when people are simply legally present in the applicable country. With several nearby countries recently joining in the scheme, Vietnam for instance, chances are if you can show you have entered legally (passport stamp) and are physically present at the time of application it will not be an issue.
I arrived by land from Laos earlier this year, TM6 completed on entry. I lost/binned the departure section and left by air from BKK a few weeks later, same passport. Nothing was asked.
To rent a condo all they will want is their money, they won't worry where it's coming from. You could easily pay direct to their account using Wise or similar until your local account is up and running. Yes you'll need to get the account sorted and funded within the first couple of weeks it you 90 day entry.
In which case I wouldn't waste my time or certainly money on an agent chasing around for a bank account on your short holiday.
Simply get a non-O in the UK when you get back. You can show money in a UK account for that. Then you'll get a 90 day entry in Q1, can easily open a bank account yourself (you will likely need to show some kind of rental contract for accommodation). You'll also avoid airline check-in questions about onward tickets.
So it seems the answer to your question "? Is 100/hour suitable for part-time maid in CM?" is NO. But nevertheless it's good to know that paying a reasonable rate you got a good job done, let's hope it continues.