you will need 3 form per extension you are applying for. TM.7, STM.2 and acknowledgement of fines. So if there is two of you applying you will need 2 copies of each of the above. On the back at the bottom of the TM.7 under your signature make sure you write a telephone number they can contact you on.
You will also need a photocopy of your passport bio page and the stamp you got when you entered (sign each one) and a 6x4 passport photo.
you can go upto 30 days before expiry so the 29th is fine.
However, regardless of what day or date you are going I would recommend going a day or two before to get the paperwork.
The day you are going for the extension, arriving at IT Square at around 8am going straight upto immigration and standing at the first counter 1 (back wall where the paperwork is) is the quickest way to get it done if you want to be in and out within 30min-1hr. Otherwise you will be spending 2-4 hours there just waiting to be seen and getting your passport back.
The former question I don't know but the latter, you get a Tourist Visa from a Thai embassy which can be extended by 30 days giving you a total of 90 days or you can do border runs, enter under Visa Exempt and extend by 30 giving you a total of 60 days and if you decide you want longer, exit and re-enter the country for a fresh exemption stamp which can also be extended.
I could be wrong as it's from a Thai university but to my understanding you will still need the transcripts for the work permit and non-b (if you're getting a non-b instead of a non-o.) Also the visa exemption can only be extended once by 30 days and then you have to leave again.
If you want to save hassle and you're going to be coming and going just get a multiple re-entry permit (3800฿) you get your re-entry permit from an immigration office (TM.8)
You can get an extension (assuming you haven't already) from your local immigration office. 3 forms to fill out, bring 2 passport photos, a TM.30 receipt, copy of bio page and copy of entry stamp plus 1900baht. (You can get your TM.30 receipt from the hotel you're staying at, you might not need it but it's better to have it in case they ask for it)