How long does strawberry top syrup last?

Stored in the fridge in an airtight container, it will keep for about 1 to 2 weeks.

Can I freeze the syrup?

Yes, you can freeze it in small containers for longer storage.

Yes, just let it simmer a little longer during the second cooking stage. But keep in mind it will thicken more as it cools down.

Yes, they work great, and you can add them right to the pot without thawing.