Hi, Sorry but this is long.

Recently I had noticed that my car had started drifting towards the left on a straight road. Assuming it to be an alignment issue I took it to the work shop where the front tires were swapped. The car still kept pulling towards the left. The mechanic then raised the car to inspect and said I had a leaking left shock absorber that needed replacement. On noticing it , I observed it was leaking compared to the right shock which was dry. Shock replacement was done,wheel alignment done and we took it for a test ride. Car now started pulling towards the right!! I was then told the brake cylinder (drums) on the left needs to be replaced because it had seals that were worn out/damaged. He also mentioned that the right brakes were more effective than the left ones. None of which made sense to me because the pulling wasn't while driving, but I went ahead and got the left cylinder replaced. Test drove it and it was way better. The car did not pull, but now I had a pedal that was vibrating. I was told it is normal and that would go away after I drive. Now my questions are.. Was the shock replacement necessary? Why did the car pull to the right after the left shock was replaced and wheel alignment done ? Was it really an issue with the brake cylinder on the left? (Drum brake) What do I do about the vibrating pedal? Please help.. I'm sorry this was too long.