I hate 'ta' - just my personal opinion. Both of mine have said thank you, not ta.
- How much of the time does he/she say please and thank you without being prompted?
W regularly says thank you - if someone opens a door for us or if someone gives him something. He's never said please. But then he doesn't really ask for anything
he just moans and points instead People have remarked on E's good manners since he was tiny. I'm finding I have to remind him now at times (usually just because he's distracted) although only with me, he's always very polite with others.
- How 'strict' are you about reminding them to thank you for stuff you give them? e.g. Would you expect/prompt for a thank you when you give them their dinner and then again when you give them their water a few minutes after?
I expect a thank you for everything. If I don't get it voluntarily, I prompt them. E will sometimes say 'I want some milk' for example, and I will say well when you ask me nicely I'll consider it. So then it is 'I would like some milk please'. Job done.
- Do you prompt other children for please and thank you when they ask you for something/you give them something?
No. Other people's children, other peoples rules/expectations. But I find that when my children say thanks you, the others tend to follow suit.
- Other than an immediate please and thank you, do you expect them to say anything else to you or others? e.g. to shop assistants or when leaving a friend's house.
I always say to E 'say thank you for having me/us' and 'thanks for the X' if they've been given food etc. My children always say bye bye to checkout operators and stuff like that. E went through a phase of shouting 'cheers mate' at delivery drivers for a while

That's from his dad obviously, not me!
My children don't ask to get down from the table but that's somethng that will come with time. They're only little. I will have different expectations of them when they are, say 5 or 6 to when they're 3 and under. I struggle to get E to eat anything atm so I draw the line at sitting on his chair properly, anything else would be a bonus