2 were completely right
1 was almost completely right (SN2 instead of SN1, something which I wouldn't have known because the textbook says that particular reagent, unusually, almost always goes via SN1 despite being primary)
1 would have been right if I'd trusted my instincts
and the last was bollocks only because I'd produced an extra C=C bond from nowhere and got myself confused. Without that, it would have made sense and I'd have been able to finish it.
Apparently I am not actually stupid at organic chemistry. I just need a lot more practice so that I trust myself in unfamiliar cases.
