Plenty of ways to use cannabis without smoking (combustion). Examples include edibles, vaporizers, suppositories, and topicals. You’ve heard of the nicotine patch but did you know they have THC patches?

Not a huge problem when we die from diabetes or heart disease first.

Something being bad for your lungs is presumably going to be very bad for your heart.

Marshmallow leaf is often used as an alternative for those seeking to quit tobacco, and does have known health benefits:

https://www.real-leaf.com/blogs/realleaf-blog/smoking-marshm...

Although certainly any combusted plant will produce tar, and this is well known to cause pulmonary issues which will indeed place more stress upon the heart.