I have a studio in the basement. I love it . No one knows its all down there , and I can leave it as is and come back without the stress of looking at my mess.
I am in IL. so our "conditions" are similar. A few things , do get a dehumidifer both for the fabric and the machine. Computerized machines do not like prolonged humidity. This is a summer issue. I love sewing there in the summer as it is so cool. But do get a space heater for the winter. I preheat the space for about 20 minutes before sewing. Its surprising how much heat comes off the iron , so once I am into it , I turn off the space heater.
I put lots of flouesant lights in the space so its like daylight in my room.... but any light will fade fabric over time , so plan for how to keep your stash from the light exposure.
Consider purchasing a battery backup for your sump pump on the rare chance that a power outage might cause a flood, they are called an "ace inthe Hole".
I do some times miss a window but find having it out of sight from the rest of the house is worth the trade off.
Oh one last tip, inthe winter I wear wool socks , sounds like not a big deal ... but it really made a huge differnce since the floor is always cool. The dogs love that I am down there in the summer , as they love the cool floor.