I believe you can rent it out if you assign it to an agent, although the rental contract must be for a minimum of 1 year. I might be wrong, but the law also says you must assign it to an agent, meaning you can't do it yourself if you're not a registered broker.
The article could be interpreted as stating that eVisas will become policy starting January 1, 2025. However, the word ‘anywhere’ makes things somewhat intriguing. I’d probably agree with you, but the possibility still exists.
Starting January 1, 2025, it should be possible to apply for visas from anywhere in the world. If your visa is pending approval next year, you could simply do a quick border run to activate your DTV. Keep us updated, it will be interesting to know.
I’m not sure about the last part. I don’t think you need to stay where you apply until the visa is approved. For example, if someone applies for a Thai visa in Malaysia but travels to Singapore or Thailand while waiting, it shouldn’t matter. The location selection likely just determines which embassy processes the application. You must be there to submit it, but staying until approval seems unclear.
In many cases, you may not receive an entry stamp in your passport these days due to the use of ETA (Electronic Travel Authorization). Instead, you can provide a hotel or Airbnb booking along with the payment receipt as proof of your stay.
As far as I know, there have never been set limits for entering Thailand by air, but they enforced a rule a couple of years ago limiting land border crossings to two times.