There are numerous posts about tax in this group so suggest you do a search. If you stay 180 days you can be considered a tax resident in Thailand, regardless of what visa you are on. Every situation is different depending on tax treaties, amount and numerous other factors that would be better discussed with a tax accountant.
as John and John have mentioned language doesn't show under soft power. 1 person posted about being successful but several posted about being denied. It clearly states what qualifies under soft power so your best idea is to pursue a category that has proven success like Muay Thai with a gym that has a proven track record, several who post in the group regularly. Either that or pay an agent to help you as it really seems you are getting confused and starting to consider a risky option.
Unlikely, education is not listed under the soft power categories of the DTV. Someone had reported they were successful at the London embassy but other have since reported they were denied.
Depends on the embassy but most want to see the money in an immediatly accesible bank accout. Search the group this question gets asked and answered daily with info from different embassies
it already has impacted embassies in nearby countries. They are asking for proof of exit from Thailand and entry stamps to the country you apply to. Some are adding the requirement that you must remain in the country until your visa is issued and are calling in random people for interviews.
The majority of embassies want it to be a liquid asset in a immediately accessible account. If you join The Destination Thailand Visa (DTV) group you'll see that people have been denied using investment accounts, crypto, etc. Check with the embassy you are applying at for what they will accept.
It depends on what embassy you apply at. Some want each to have 500k THB, others are good with just one of you having it. If it's a joint account some want to see 1mm THB others don't.