car seat accident replacement

I have a car seat dilemma?

I have 2 questions. First I was thinking about using my son’s old infant seat for the new baby. We bought it last spring so he was only in it for 5 or 6 months. We were in a car accident so for me buying a new one was mandatory and this was the replacement. The infant seat we have is nice, clean, and we considered it safe for our older son, is there any reason we shouldn’t consider it safe for the new baby?
Second I drive a small car. How do I arrange the car seats in the back seat? If I put the infant seat in the middle, my older son’s forward facing seat won’t fit (at least I don’t think). Do I put the infant seat on the drivers side or passenger side? Thanks in advance for your knowledgeable answers.

infant r-rear facing backwards/other l/rear facing front

SPD offering safety seats to parents in need
Remember what child safety seats used to look like? They were a white plastic and nylon tub you belted into the back seat of your car, and if you had an accident, well, they might or might not hold the child, depending on the quality of the seat and how well you’d installed it in the vehicle.