1) It depends entirely upon the quotes, and who said them. Some quotes are directly attributable to people, either in speech or texts. If you wanted something like 'better late than never', then no, you don't need to credit the originator. This is either because the saying was coined by someone who has been deceased for more than 70 years, or because the phrase came about from language's evolution and the public conscience, and isn't attributable to any one person. (See no.2 below for extra information)
2) If you want something like 'get busy living or get busy dying', which is my favourite quote from the Shawshank Redemption, then you're on shakier ground. The script of this film is copyrighted, and it's arguable that you're taking a substantial part of the work that you had access to. Bear in mind that substantiality can be measured qualitatively, and not just quantitatively. I can't say for sure if you would be infringing- that's a matter to be argued in a court- but I'd be wary of doing this.
If you do want to use well known phrases that are copyrighted- music lyrics or modern film quotes, for example- you will need a licence from the copyright holder ( who may not be the same person/company as the creator). Follow this link for preliminary information:
http://www.cla.co.uk/ . In these cases it isn't enough to simply credit the author, as your actions with the copyright don't fall under any permitted acts in UK law.