For me, it has been. I just try to think about it before I do anything or talk about it, even aloud to myself and sometimes it helps but I still struggle lol

For some people it can be. Being on the spectrum means that ones executive functions (abilities to multitask, stay focused on non-interesting things, look at things from different perspectives) are taxed constantly. Inhibitory control is one of them, and impulsiveness is something I’ve had to work on a lot in life. The good news is that executive functions can be developed and strengthened through mindful practice!

It is a common symptom... Mindfulness and spending time with people who will call you on it when you start to behave this way can help (but you have to be willing to listen to them). Keeping anxiety and depression in check really helps too and if you're a spiritual person (I personally think if not, that's part of the problem but that is strictly my opinion), staying grounded in your faith can help. Practices that require discipline, such as a diet, exercise regimen or daily cold showers help. Gardening or cleaning can help, as can engaging in a productive hobby such as crochet or painting... I'm personally starting to do a lot better and these are the things that have worked for me. I sincerely hope this helps.

Yes, but only because of ASDs high comorbidity with ADHD (50-80%). (It used to be thought that hyperactivity could be an autism trait, but that was reevaluated in 2013 when comorbid ADHD and ASD diagnosis’s were allowed). If you feel like you are very impulsive I would recommend looking at the DSM5 criteria for ADHD as it is very easy to understand.