No. The only thing immigration office accepts is embassy certified income. The US embassy does not do this anymore for many years. So income is not an option for your first extension. You can use 12 months proof of monthly international transfers for subsequent years, but the first year will always be 800k in your Thai bank account.
There isn't now, nor has there ever been a 6 month rule. But if immigration thinks you're spending more time than a typical tourist in Thailand (6 months is definitely not a typical tourist), expect to run into trouble.
I'm not sure what you're asking. TM30 is required by every property owner to be filed within 24 hours of a Thai arriving at their property. It has nothing to do with residency. Whether it's to spend 1 night or 100, it's the same requirement.