I'm quite sure there are immigration officers working at land border crossings that knows about the "2 border runs per calendar year" limit,but I'm also sure there are officers that haven't got a clue. It's a bit of a gamble I guess.
What new rules? Fyi, I've been banking with that branch many years and if I'm saying that's the easiest bank when it comes to open a savings account, then it is. You seem like a guy who uses agents. Don't argue against better knowledge.
In Jomtien,there's no need for an agent.Bangkok Banks branch on Jomtien Second Rd is probably the smoothest bank in Thailand when it comes to open a savings account.