First and foremost, it is important to know that Astral Travel varies from person to person, and not everyone will experience negative/positive things from it. So with each individual, it is important to learn how you feel about it.
Ok to the first question: About being able to easily leave your body. It can be dangerous to a point. You might wonder off. The link to your body may (may being the key word) be weaker or more faint as a result of this (it depends).
This can easily be solved by tying yourself to your body, create a link, or even leave a “Trail of bread crumbs”
You can even create an artificial entity that’s sole purpose is to assist you into getting to your body. There are a lot of different solutions to this.
Second question: Personal experience below
I’ve actually had the opposite happen. I feel the pain that my physical body has. It transfers to my astral form. When I had a kidney infection, I could feel the after effects in my astral form for weeks.
I can even get aches, bruises, and be in pain because of what happens to my astral body. So it can transfer the other way as well.
Of course, it varies from person to person. My astral body and physical form are just very closely linked