If you put the teats and lids on they should be fine to be stored outside of it up to 24hrs. However I mainly kept them inside it unless I was going out for the day, they did fade eventually but didn’t cause any major issues, I still used them.
Our dr browns bottles survived the Milton tank! They wore down a bit but I would expect that really, never to the point we couldn’t see the markings though
As long as you make the bottles up you can leave bottles out for 24 hours and they’re totally fine. We had a set point on our worktop that bottles were put x
To my knowledge I don’t think there is a way to safely store sterilised bottles as you’d be transferring them into something which isn’t sterilised therefore meaning you’d need to sterilise the bottles again. But I could be wrong? I’m 34 weeks pregnant and planning on using the Milton cold steriliser as well