I am growing veggies in containers and have a couple of questions. Any and all insight you can offer would be great! New to this whole thing- especially in winter :)

1)General question

~At what temperature should I be covering all my plants (veggies, herbs, flowers) at night with sheets? I have never lived in cold climate before so this is all new to me!

2) tomatoes

~I got a late start with my recent batch of tomatoes and they are all at different stages, some with fruit some still seedlings. I am wondering, with weather getting colder how long they might still have a chance to grow for or if I should just give up on them.

3)Radishes and Carrots

~I know radishes do well in winter so I plan to keep those going but unsure about carrots...can I plant them as well this time of year in pots and get some "salad toppers"? (fyi these are mini varieties- sparkler radishes and baby finger carrots)

4)Spinach and Lettuce

~I have spinach (melody variety) that I know will stand up in freezing temperatures. What about lettuce? I have very small head variety (forget the name) that is producing leaves currently but wodnering if that will stop and/or if I will be able to plant more!

5) Herbs

~I am hoping to bring my herbs indoors but in case I can't...is there anything than can survive winters outdoors? I have the following herbs at the moment: sage, dill, parsley, cilantro, thyme, catnip, oregano, rosemary

~ ALSO, is there any form of basil that survives outdoors in the winter? All of my plants are fading fast and havent moved beyond two leaf pairs each. I would hate to have nothing to use until warmer weather... (sadly lost all my freezer supplies to a tragic electrical malfunction). IF NOT: what kind do you recommend to grow indoors with limited light available?