Help needed with various aspects of text input and editing on iOS

first I'm using a jailbroken iPhone 6 Plus with iOS 8.1.1 with Alex as my voice.
1. How do you insert a letter if you are typing and you screw up using the keyboard on the iPhone 6 plus? I've had this explained to me on twitter but really don't understand it. something about depending on which way you flick when you are on the roder? I have characters and words in my roder. I know how to activate the roder to get to the word or characters, and I know how to flick up and down to go forward or back on each. That's the easy part. Its editing to get the character or word where I want that I cant figure out.
2. If I want to select a word to perform an action on it, such as copying or deleting it, is there a way to do selection on the iPhone? how would I select a word then copy, paste or delete things?
3. i hear you are suppose to be able to hold the delete butten down on the phone to have it delete characters really fast. this never works for me. If I tap delete, it deletes one character at a time. If I hold the delete butten down, it just sits there and does nothing. If I want to do continual deletion, i have to keep tapping the butten over and over. Is it because I am jailbroken that this does not work, or am i doing something very wrong?
3. Also, would somebody be willing to help me how to use the apple keyboard? here's what I know so far.
the very top write key shows or hides the phones keyboard.
Up and down arrow together: double tap
Left+up arrow or Right+up arrow: goes to the different items on the roder.
left or right arrow, flicks left or right on the screen
if in one of the settings on the roder, up and down arrow moves you back and forth
second key on the top left: decrees brightness
third key on the top left: increase brightness
Past that, I have no clue. dunno what the other buttens are. I can type easily enough on it.
I may be taking on way too much at one shot, but figured I'ge all my questions out at once. I've only owned an iPhone since December 23rd, 2014 so not a seasoned pro. Thanks!