I still feel the linked thread actually covered your inquiry and much of your new questions pretty well.
You can use any plugin or library you wish to include in your projects both free or paid. Just implement each in accordance to their respective provided documentation setup & usage (HTML/CSS/JS) for whichever ones you choose to utilize in your projects.
PS: You got a rare response in your Copy & Paste feature thread that you should respond to if you have not already privately.