Alrighty, brain seems to be functioning better this morning, I think.
What I'm seeing is that you're pushing A time with the aim of dropping the CN and getting long naps again. Essentially, LO may require a little help to get through the first few days of new A times, so just helping he get through that 30min waking by being there at 25min and watching for him to stir and holding his arms to prevent them flapping or just putting a hand on him to help him settle may help. If he's somewhere different from where he fell asleep, he may be waking due to that, so yes, independent sleep will help both naps and night - so much more practise for him to do both at the same time
Its the same skill.
PUPD is difficult to sustain. There are other ways that should be tried first. I can help you work out what might suit him best if you like:
How is he currently getting to sleep?
How do you ideally want him to go to sleep?
Are there any limitations to your ability to do sleep training - must shut in chooks at 5pm regardless, or whatever?
What is his personality/temperament?
The BW "Know Your Baby Quiz"