Car seats and Strollers

Help! I’m a first time mom-to-be and reading all these car seat and stroller recommendations/reviews is confusing me.

I’m pretty sure I want a travel option that goes from car to stroller. That seems to make sense.

1. Do I get an infant car seat if they’re just going to grow out of it in a few months?

2. Do the bigger convertible car seats fit in the stroller?

3. Are the convertible car seats appropriate for infants?

4. If we are planning on a second baby close in age, would you get a product that converts to a double stroller?

Thanks for the help ladies!!