I don’t have all the answers but will try with a few.
Be careful with shush pat as this may annoy them you’ll have to see had they react.
We started with night time then naps the following day then every other sleep time.
If you can get help from your partner do it, both be committed LO will cry and it is hard but take it in term 2 days on 2 days off, just the one person doing it at the same time no swapping.
Yes PU/PD after feed, you’re teaching them to go to sleep themselves not via food etc, so if they’re asleep give them a little nudge before putting them down.
Room should be calm and relaxed, use your judgement that a small none bright nightlight should be fine as long as it doesn’t distract.
Hope that’s a help.