I suppose it really should depend on the region the speaker comes from. British English speakers don't say 'Kum-muh the store'. There is a very distinct but barely stressed 't' sound in between 'come' and 'the' - come tə ðə store. 'To' and 'the' are pronounced with the same unstressed schwa sound, but the consonant is said lightly in both. Omitting the 't' sound may be common in some places but it is not something I ever hear.

1a - correct 1b - not correct at all 2a - correct 2b - not correct at all 3a - not quite correct. Should be 'has' and not 'had' 3b - not correct at all 4 - both incorrect

It isn't an adverbial of purpose. But it's not really attributive either because it's not modifying a noun. It is modifying the whole phrase 'has done more'. What do you think it is?

'As if he were under her spell' is correct. Using 'had been' places this as a completed action before 'followed' meaning that he is no longer under her spell. And this is not true.

It is correct to say it. It is hard to say whether but sounds natural or not because it is just not commonly said. It is more precise than promoted if you mean that this idea is not entirely true. If the country is genuinely under threat, promote is better.

They both have the same meaning - the last time I played sports was 15 years ago. 'I haven't played sports for 15 years' has an additional interpretation. It could mean that the person has played sports continuously for some time but that time is not 15 years. It is 10 years for example. But this would be very rare, and would be clear from the context. Without context, it has the same meaning as the other phrase.

I agree with Daisy. Looking at Google ngrams, you can see that your suggested phrase barely exists.[Image]

It is absolutely a general truth. The em dashes indicate it is a parenthetical statement. That person who did not remove their shoes did not do so because it is a general truth that removing shoes breaks their rule.