Ill chime in, as I also live in chicago :) and had babies. :)
TBH, I did not use a stroller with my first until she was 3. I had a variety of slings, and carried her, well past her 2nd birthday, almost all of the time. She wasnt a heavy baby-I think at 2 she was still under 25 lbs. I also drove mostly to and from places. I didnt really use cta at that time. One thing that was awesome was having a babywearing coat, that I could wear her in a sling underneath the coat.
When I had my second, though, I started using the stroller more, but put the toddler in it and carried the baby. The stroller is nice because you can put your stuff in it :) Diaper bag, lunch, waterbottles, :)
The thing about strollers is you can always find second hand ones- on CL or virtual garage sales on FB, or at play it again sports store, or thrift store...etc. I had a jogging stroller from the thrift store that lasted a couple years for 10$. That thing was amazing. it survived several plane trips, and a few summers at the beach (nice big tires go over sand, as well as bumpy sidewalks) I think umbrella strollers are kind of useless (and the handles are always too short for me so I have to hunch and its uncomfortable.
It still folded up pretty well, and fit in my trunk of my civic. It was a step-up brand (not high end or fancy) but it served me well. and hey, you could also jog with it (if you had to. lol )
Its true that strollers on the bus are a major PITA. some trains less so. but obviously, people make it work if they have to. I have friends without cars who make it work with multiple children and slings and a stroller and a lot of walking :)
but I dont necessarily think it has to be gotten ahead of time, and if you are planning to use a sling, you dont need a stroller until later anyway. get it secondhand, sell it off if its not useful.
Now, if you want to talk slings....I highly recommend finding a way to try a few kinds out. I dont know if there are still active babywearing groups around, there used to be, and they had lending libraries of slings! or go to a La Leche League meeting and ask around if anyone has recommendations or one they can let you try on or borrow.
I personally loved the pouch style sling. Its sized to the wearer, so you and your partner or other caregivers may need different sizes, or one size might fit you both. I used a pouch with both kids for most everyday from infancy until toddler age. I also ended up liking a ring sling when my kids were older and more in-out-up-down. Most of my friends liked ergo or similar carriers, but I never liked back carries, so I never got one. Mobys are fantastic when you have a small infant, but they get uncomfortable as baby gets heavier and can be inconvenient to tie on.
So exciting to have a new baby! or baby on the way! :) yay!