If you have printed the bank statements yourself they will need to be stamped on every page by the bank or accompanied by a letter confirming their authenticity.
Payslips that you have printed must be accompanied by a letter from your employer confirming that they are authentic.
https://www.gov.uk/guidance/immigration-rules/immigration-rules-appendix-fm-se-family-members-specified-evidence
This is where it starts to get confusing with the rule changes, as the rules you quoted in the post above have not been amended recently.
If I have an original bank statement received by post, it would now appear to be permissible to make a copy of that and send it with the application. However, if I print out an online bank statement, I would need it to be stamped by the bank or to provide an 'original' letter from the bank on letterhead paper confirming it's authenticity. I assume that it would then be permissible to make copies of the stamped online statements or the 'original' letter from the bank and then send those with the application ?
In regards to letters of confirmation of employment, if an employer scans a signed letter written on letterhead paper, and then sends that to me via email, would a computer print out of that be considered an acceptable copy ? Or would I need to have physically received that signed letter myself and then make a copy of it which would be sent with the application ?
I apologise for these extremely picky and pedantic questions, I was just want to be absolutely sure. As usual with Home Office rules, the specifics concerning rule changes are undoubtedly going to be quite confusing, however it's always better to be safe than sorry.