Is it sacrilege to modify this guy?

I’ll be honest I know nothing about bikes. But I do love this thing. However I just now started riding it everyday to work, which is only a 25min ride. But I only really use two gears, I don't like how it shifts, it constantly wants fall into another gear when I start off again after a red light. And the wheel is slightly bent in the back from a nasty pot hole.

I don’t want to own two bikes and I’m not getting rid of this one so its either modify it or suck it up.

Also I don’t really know a lot about the bike if anyone has any insights. I’ve had it for years but always forgot to do more googling.