just a few things i'd like to point out/suggest...
1) you may want to move your fish to your friends tank just untill you get yours cycled, i know it will be a pain but in the end it will be sooo worth it.
the nice thing about a fishless cycle is you don't technically need to do water changes until the very end of the cycle when you see the Nitrite spike and then vanish. all you have to do during this fishless cycle is add a small-ish amount of ammonia every day.
2) if option #1 is not something you want to do they i would really suggest you invest in a "Water Changer" see the link below... i have a 55G and a 125G and let me tell you, the water changer is amazing. you can do a 50% water change on a 55G in about 30-45 minutes if not less. it saved my back lol (i used to change water with 5 gallon buckets, never again will i do that)
Aqueon® Aquarium Water Changer - Aquarium Maintenance - Fish - PetSmart
3) water changes should be done every day or every other day during the initial cycle, after that its normally once a week but thats dependant on your NitrAte levels since you want to keep them below 20 if at all possible.
most people will tell you that you "can never change too much water" which in most cases is correct but you need to use common sense as well lol, the most i would do at one time is 70% and that should be only in an emergancy. 50% is gonna be where you want to stay now but my whole point is that you could do multiple water changes a day if need be but just don't change anymore than 70% at a time. if you do this you run the risk of shocking and stressing your fish to death.
a fish-in cycle is definitely a pain in the butt and requires a lot of work from the owner. i fish-in cycled my 55 and i'll never do a fish-in cycle again.
4) is there any way you could test your tap for ammonia, nitrite and nitrate and post it here so we can all take a look and see where to advise you??
most importantly, please dont think i'm trying to rip you a new one... just trying to be helpful.
also, i know this thing is full of mispelling and what not lol... just ignore them