Just Married in December. Questions about filing for 2025

Hi all!
My partner and I just got married in mid December (We live in Georgia- rent, don't own) and I have some questions about the smartest way to file our taxes for 2025. Some info about us and our income:

Me: 1.) salary of 55-ish a year as a manager at a dog daycare 2.) I sell some of my items on ebay as a side hustle and have made about $5k off of that in 2025 3.) I do independent pet sitting out of my house to also get some extra income and have made $6.9k from that this year.

Her: 1.) Salary of $63-ish a year 2.) She sells her clothes and such on Poshmark and has made about $3kish in 2025 off of it.

My questions are as follows:
1.) should we file separately or jointly? Which option would be smarter or offer a better return?
2.) Do we have to claim any of our additional income sources even if it is just pet sitting for friends and selling our own belongings?