I'm not sure if they're doing interviews for ED visas or not. But 5 working days after paying is likely close to what it would be if there's no interview.
Each immigration office has their own policy on when you have to do a TM30. You should ask your immigration office what their policy is. Some want it every time you leave your home and return to the same address. Some only want it if you leave Thailand and return to the same address.
If you already have 800,000 in a Thai bank, why would you get a non-OA visa? The entire point of the non-OA is so you don't have to keep money in a Thai bank, but instead have to buy insurance. If you have the money in a Thai bank, then get a non-O and you no longer have to get the insurance from the special list of companies.
In Laos everything is done online except for the payment. You submit online, then go between 9-11 to pay after submission. Then you wait for the visa. I don't think Non-B requires an interview, but it's always possible if they want to verify you are still in Laos.
There are a couple of immigration offices that have recent reports of requiring a bank statement when transferring your extension stamp (not transferring your visa, you cannot transfer a visa). If you have an extension based on retirement and are using anything other than embassy verified income, then you have a requirement to keep money in your bank during the time between extensions. Some immigration offices are requiring you to show that you have continued to meet your requirement since you got your extension in order to move your extension to a new passport.
If you don't have an extension based on retirement, then this likely doesn't apply to you.
One Bangkok is only for people with a work permit or LTR visa. You cannot do your 90 day report at One Bangkok. Everyone else must do theirs at the main immigration office at Chaeng Watthana.
In all my years in Thailand I've literally never heard or seen ANYONE put KB for Kasikorn Bank. How am I supposed to know it's Kasikorn Bank? Why not Krungthai Bank? Why not Krungsri Bank? Maybe there is some kind of account or investment firm with the name or initials of KB. So No, I am not going to "guess" what KB means when it comes to immigration.
there is no ATM between the plane and immigration. If they ask to see the CASH and you don't have the 20,000 baht, they'll deny entry and hold you until you pay for a new flight out. Normally only for people abusing tourist entries. But better safe than sorry.