Most Thai banks are phasing out internet banking except for business accounts. Everything is done by phone app now and the phone number (SIM) must be registered to the same name as the one on the bank account.
None. This visa is not used. The only people who used to use it were Australians because their embassy accepted showing money in an Australian bank account but now everyone is on evisa so this visa is basically dead.
If you are talking about a Thai address, you must go to your immigration office and apply for a residence certificate. The address will be based on where you stay, as that's where your TM30 will be filed by the property owner.
6. Applicant must have a bank deposit of no less than 800,000 Baht in the last three months
or an income certificate (an original copy) with a monthly income of not less than 65,000 Baht,
or a deposit account plus a monthly income totaling not less than 800,000 Baht (in one year). In the case of submitting a bank statement, a letter of guarantee from the bank (an original copy) is required.
Nothing there says anything about a Thai bank account or a certificate from any embassy. You are not dealing with immigration which has a requirement for Thai bank account, you are dealing with an embassy.
But you cannot just "get" an education visa. You need documentation from their school in order to get an education visa. Are they already enrolled in a school who has told you they will support education visas?