Congratulations. You will love the drive if it's maintained well. I had also bought a Reborn Oriel with 104km in 2021.
You should consider Honda original synthetic oil. Zic X7 is also a good oil.
Also, you should ask the seller about previous oil change. If he can't tell, you should play it safe and replace esp. engine oil (about 4 liters), coolant (Zic+ 4 bottles) and Power Steering oil (Honda original). No need to change gear oil unless it is dirty. Your mechanic will tell you. My mechanic told me to just top it with dw3 gear oil Saikin brand.
I also recommend AC and radiator check and service.
A slight jerk when gear change is normal as it's not a CVT like the latest gen cars.
No idea about the loud noise on acceleration. My Honda doesn't do that. You should get it serviced by your mechanic. It might need new spark plugs or tuning. Again, your mechanic will recommend the right step after inspection.
PS. I find it hard to believe that a 12 years old car has only 48k!