なんか is a filler word with a similar use to the english word 'like'. It's purpose it to give the speaker time to think in the same way that we use umm/uhhh. Basically don't read filler words as their literal meaning. In english if someone says whilst thinking "I went to that new store that opened up but they were all sold out of... oh what's the word.... oh yeah scrunchies" this can be thought of in the same way. So using this yourself instead of using english fillers will help you sound more fluent. I personally prefer えと as it rolls easier and you can extend it when thinking for longer. ～ね like you say is usually used to seek agreement. ちょっとまってね. - is like wait here ok? - ね being like "alright?" ～よ is used to make a point or show that you are agreeing with the speaker. It is useful to use then when you are responding to someone and agreeing with the point they have made.