Yes, seems absolutely realistic. I just ran my first marathon last week in 3:49, with slightly more mileage/long runs than you but slower training pace. To be more specific, I followed the Hal Higdon Intermediate 1 plan other than slacking on the cross training. Easy pace about 10/mile, did some of the tempo runs at easy pace if the legs didn't want to speed up, and a did strides at the end of some workouts during the taper. Same age and only started running a year ago. I felt like I could have gone a few minutes faster - my last couple of miles were the fastest, and I was exhausted and in pain by the end of it but not as much as expected.
Regarding running with the pacer - depends on how congested the road is behind the pacer. My plan for my marathon was to run behind the 4:00 pacer for the first half and then assess if I can speed up, but it was so packed and uncomfortable to run in this mass of people that I ran in front of the pacer shortly after the start and just set my own speed by checking my pace and heart rate on my watch frequently. I just found someone to run behind, and then if they were going too slow or fast looked for the next person to follow.
Do one or two 20 mile runs before tapering and get your nutrition before and during the race dialed in so you don't hit the wall after 20 miles, don't do anything stupid on race day, and you'll make your goal.