FLR-(M) extension. help with support documents and some ques

[Jaimevillrios]

Hello and thank you in advance for taking the time to read and reply to my post.

Im about to apply for my first extension (after 2.5 years) on my spouse/partner resident permit that was granted to me on 12-11-2014 and expires on the 12-05-2017, my wife (sponsor) is british and im planning on booking a premium appointment for the beginning of may, and i would like help with some doubts that i have about the supporting documents.

General information: i enter the uk on may 2010 with a tier 4 student visa and been living here since, and moved my status to spouse/partner on a 5 year route on 12-11-2014.
My wife meets the financial requirements as she earns £24k a year, plus i can provide proof of employment and payslips for the past 6 months.

1- first of all my wife and i have been living together on the same address for more than 3 years. but we have never put all our bills or documents in join names , so i would like to know if the documents that im planning to provide for proof of cohabitation will be enough for the application to be successful. the documents are:

-rent contracts renewals in both our names for the past 3 years.
-council tax for the past two years in both our names
-join savings bank account statements (my doubt with this is the saving account is not been used much just casually and in between long periods of time and the statements would be printed from the online pdf files )can it be used?
- Individual NHS cards from the same GP practice. (is this useful?)

Now for the solo documents in the same address.

sponsors documents:
-pay slips going back two years
-bank statements from natwest. (we are planning to print the bank statements from the online pdf files as the bank dont send montly statements )( we used this printed pdf statements for my initial spouse/partner leave to remain application before successfully.) is this still viable or is better to request the bank to print and send us the statements for the last two years if possible?
-water bill for the last two years
- some nhs letters
-car insurance documents
-credit card statements
-dvla letters

My solo documents:
-Bank statements from natwest (same scenario as my wife)
-credit card statement ( this are posted to me monthly, but the statements dont go back the whole two years, i got this credit card only for over 1.5 years) still good to put as proof?
-Bank statement from barclays for over two years (statements posted to me monthly)
-gas and electricity bills for two years
-can i print online bills from my mobile, tv and internet providers and use them?
-tv license ( less than two years though)
-pay slips ( only 6 months)

thats all the documents i think i have as proof of cohabitation and are pretty much the same type of documents that we provided for my current spouse/partner leave to remain.

2- My wife is pregnant right now over 7 months, and we have some nhs documents that has both our names as mother and father. can my wifes pregnancy and documents can be use as proof of our relationship or in a positive way for the application? and does her pregnancy affects my application in any shape or form without our baby being born yet?

3- is it necessary or a good idea to include photos of us and stuff like holiday plane tickets as proof of our relationship?

4- is it necessary to for me or my wife to make any type of cover letters for the application?

5- can someone advice if i can use another type of documents that i might no be including.

sorry for the long post and thank you for your time and response to whoever has good advice for me.
Thank you!!!