My 7-8 month old Grey has 4-5 contact calls. One of them is extremely annoying. 2-3 are not too bad, and one of them is very cute. She doesn't talk yet - but that normally doesn't happen until they get a bit older. Yours is right in the age that they will normally learn to talk - so be sure to talk to him often.
Regarding the noises that you find annoying, here's what has worked for me:
My Grey used to make all her calls in roughly the same frequency, but I started making the one I liked best back at her EVERY time she used it, to make sure she would feel rewarded every time she tried to make this contact sound at my wife and I (my wife does this as well). With the 2-3 that are OK, I would still make the call that I liked the best back at her every time she tried to make vocal contact when we were out of sight with each other. The one that is extremely annoying, I do not respond to in any way.
Over the course of 2-3 weeks, she has almost completely stopped making the annoying call, uses the other calls at times, but the vast majority of the time, she uses the desired call. Its been quite a change of noises that she chooses to make.
As far as talking - I would try not to worry about that. Use words in context and talk to your bird often. He may never choose to use human speech, but he will learn to communicate with you in context of what he is trying to communicate. Greys are very vocal and communicative creatures. A Grey that I had many years ago built different relationships with each person who lived with us. He used different words and different noises to communicate things, depending on who he was talking to. Try to teach him how you want him to communicate with you by example. He will understand, given enough time. He's a social animal and wants to be able to express himself to you.