How often should I send?
Monthly is a sensible baseline for most small shops. Some lists happily take fortnightly. Volume without value is now actively punished by the inbox, which is covered in what changed in the inbox.
What if I have no news this month?
Then it is built from advice, seasonal relevance, customer questions, product education or a useful reminder. Nobody needs to hear about your quiet month.
Can newsletters include offers?
Yes, and they work better when they are the smaller part of something genuinely useful.
Do you source images?
Yours are usually best for product-led sends. If there is nothing usable, I plan around that or work from existing marketing material.