1: you can do without jquery, and therefore you should. if all you need is $('#my_id') then it's overkill and it's better to save on download speed by leaving jquery out. See http://youmightnotneedjquery.com/
That said, jquery is a powerful tool and it's widely used for a reason.
2: unrestrained use of jquery, if it's your only tool, can lead to code that is hard to understand, and easy to get wrong. if any part of your code can modify any part of your page, then it is a good idea to retreat from that and be careful/organized about what you do, and when/where you do it. that organization is what JS frameworks try to help with.
you may or may not find your life is improved by such frameworks, depending on what you're doing.
1: you can do without jquery, and therefore you should. if all you need is $('#my_id') then it's overkill and it's better to save on download speed by leaving jquery out. See http://youmightnotneedjquery.com/
That said, jquery is a powerful tool and it's widely used for a reason.
2: unrestrained use of jquery, if it's your only tool, can lead to code that is hard to understand, and easy to get wrong. if any part of your code can modify any part of your page, then it is a good idea to retreat from that and be careful/organized about what you do, and when/where you do it. that organization is what JS frameworks try to help with.
you may or may not find your life is improved by such frameworks, depending on what you're doing.