Yes, Your style will override the original bootstrap's styles and in your project you will have two styles, and this will decrease the speed of the project. Still as I mentioned, Bootstrap is one of the most popular Framework and it's totally fine to use it.
Yes, Your style will override the original bootstrap's styles and in your project you will have two styles, and this will decrease the speed of the project. Still as I mentioned, Bootstrap is one of the most popular Framework and it's totally fine to use it.
Not really, bootstrap provides sass files for you to override at variable levels. Then you build the version of bootstrap you want