I filed my taxes w/ the help of my friend on his own Turbotax account. I now prefer to file using my own account. How can I transfer my info & history to my new account?

You can't.  Only if you download the .tax2018 file from online last year return.  Then you can transfer it into the Desktop program.  Or you should use your friend's Turbo Tax Account.  If you did your return in his account then it now only has your return in it.  So continue in that account.

1) That is not possible.

2) Online accounts are only good for ONE tax return.  If you tried to file a 2nd tax return  from the same account then the 2nd return overwrote and destroyed the first on.   Each online tax return requires a separate account with a unique user ID and password.