if you bring cash, or use wise or whatever, no way you going to avoid fees; how much fees and what's the best has a lot to do with how much. different methods will give better rates depending on the transfer amount.
Normally airlines have issues over 60 days without a visa but with a visa should not be any issues. Don't think they care about what type of visa really
The original post I read said "maybe December or maybe as late as June/July. Thailand always throws out these "trial balloons" that are only concepts, and people panic and think it's happening "now". The 300 baht arrival fee has been tossed around for years, and now it's in the news again, but nothing more than vapor so far.
As far as I know this is not approved/published, and still going through the government processes. and no definite starting date. many ideas are discussed, some get approved, some gets debated forever, some approved.
could just go to Thailand 60 days visa exempt, then find a local agent, does cost a bit, but quite easy and painless. They'll also get you setup with a bank account.
you can't book your return ticket based on a "possible" extension. it has to be within the initial 60 days "assuming visa exempt". Is best to get a ticket that has cancel/rebook. If you don't probably not going to be immigration, but your airlines will not even give you a boarding pass, if you do not follow the rules.