The photos must not be selfies, all must show you and your wife. 1 in kitchen, 1 in bedroom, 1 outside showing house number and 1 other. Print 2 per a4 page satisfies the requirement. For the map i generally do a google map print on top half of a4 from CW to my home, and a hand drawn on the bottom half from the nearest major SOI to my house. You need both a letter and bank statement (i always get 3 months) from the bank not older than 7 days. Copies of each page of your bank book, make sure you have over 400k in the bank. On the day you need to withdraw 100bht or so, (ensuring your still over 400k), update the bank book, get the last page copied and replace any you might have done in preperation. Note i usually do 6 photos in case they reject any.
Speak to your sister in law, get a copy of the blue book address page and a copy of her ID to upload and you can set up an online account yourself to manage.
Unless you intend on 'travelling', travel insurance wasn't what you were looking for, as it usually only covers upto 90 days after arrival. As suggested look at a health and accident policy from someone like AXA Thailand.
The school you have enrolled with should have educated you in the documentation and timelines that are required to maintain your ed visa, which i assume requires a 3 monthly extension and a document confirming your continued elegibilty.
yes, if shes on a long term rental, as Jan said she just need a copy of blue book first page, and copy of owners ID, to set up and register the address.
The IO is correct, under the law if you are returning to the previously registered accomodation within the check out period, you do not have to create a new tm30 record. However, if you need to interact with the imigration office during your stay some offices require an updated TM30 where your check in date is greater than your last arrival date. Get your girlfriend to set up an online account which means you can do it from home.
to register an address an ID card and blue book are required, (copies uploaded). This gives a user id (email address) & site password. Whoever has the ID and password can create records and print pdf. Its the owner/landlord/mamager/housemaster's accountability to ensure its done, but any authorised person can take responsibilty for actually doing the reporting if they have the id and password.
If your in a long term rental, try and arrange amicably that you get access to the online account, and do any required entries yourself. I'm assuming the agent has already created one rather than them visiting the IO everytime.