1) How to perfectly align the wheels. Shocks waghaira se bhi wheel terha ho jata hai? This is first I am reading about it. I have driven GS150SE Since December 2016 and even traveled to Islamabad from Lahore on it. If you have the Steel Wheels, then reach out to someone like who tightens the spokes in the wheels. Get the spokes gripped and ask him to check if the wheel is uneven at some point. It should fix the problem. If turning is an issue, then get the ball bearings in the handle checked. They might have gone out of shape. Get the new ones in and then try steering the bike. It should resolve the problem.
2) Koi tareeka k brakes improve ho jae (do not want disk brakes) Unfortunately, the standard drum brakes on GS150 are smaller than its size. That is why, replacing them even with a Honda, Yamaha or anything like that won't fix the issue. Get the Disc brake in the front wheel with an alloy wheel, and see how it differs the performance.
3) gear lagtay waqt aksar KHADD, KHADD krti hai, aik baar clutch cable bhi tabdeel karwa chuka hun. If it is happening since you bought it, then you need to manage the gear timing. 1st gear at 1500 rpm. 2nd gear at 20 Kms, 3rd at 40 kms, 4th at 60kms, and 5th and 80 kms. RPM ratio may go this way. 2nd at 5500, 3rd at 6000 4th at 7000 5th at 7500-8000
if the problem is fresh, then try changing the engine oil. Prefer getting a 10W 40 Synthetic oil with 4T mentioned on it. The problem is less resolved with a clutch cable. But you may also try it.
I am based in Rawalpindi, but bike theek karwane Lahore bhi ja sakta hun: Then Visit Kashif, he is at Akbar Chowk township Lahore near. Else see Ali and another guy there, I forgot his name, they are in Suzuki Showroom Workshop exactly at Akbar Chowk Lahore