[...] My next problem is that I have tried mining on 2 Bitcoin sites (Slush's pool being one of them) and I can't get my miners to work with Slush's pool at all, so I used another site and managed to get my Gridseeds to mine BUT, again I can't change the individual frequency and they only mine in scrypt mode, also all shares are rejected. [...]
You will have to mine with scrypt on a pool that supports scrypt. Slush's bitcoin pool won't.
As for settings, I used part of
https://github.com/davidmaitland/Gridseed-PiMiner and it worked out of the box for me. Did my own tweaks to it, but their config file containing
"baud=115200,freq=850,chips=5,modules=1,usefifo=0,btc=16"
works. You don't say which Gridseeds you are using though.