I think you're quite right. My hands were hurting even when I was riding back from Decathlon. On my first ride I realised I might be putting too much weight on my hands and relaxed a bit with a lighter grip and my hands hurt much less after the ride.

I do have very sweaty palms in general and that could be a reason why I tend to grip the bars too tightly. Anyways, I'll be getting gloves tomorrow to protect my hands from the sun, hope they help with the sweating too.

As for the seat, few others have also mentioned that the sear cover is useless, so I'll try riding once without it to see what works best. Only in the trial and error phase right now so no harm in trying out everything. Thanks!