The nearest land bordering crossing is Chiang Khong in Chiang Rai. Green Bus runs there from the Arcade Bus Station in Wat Ket or you can use a private van service.
Don-Laura Traub if flying south is an option, you could throw Singapore into the mix as well. Udon Thani flight then bus to the border should in theory be the cheapest option and the quickest.
They've got until April but where ever your friends go, remind them to book an appointment well in advance.
What happened after the last crackdown in around 2014 is that it was strict for a couple of years and then it eventually became lax. It won't be lax anytime soon, particularly given the alleged Chinese criminal element to the rorting.
Which is what it's supposed to be - 8 hours minimum a week and legit schools typically run them over four days a week. If you don't want to turn up to class and actually learn, go and get a proper visa.
no recent history - you will be fine. Still don't know where you currently are but if you are still in Chiang Mai, there is an increasing number of options for flights. CNX flight schedule here: