Quote Originally Posted by George1992 View Post
Can I say "Я иду за покупками" as an answer to question "Where are you going now"?
It's ok, but I would probably answer "За покупками." without "Я иду".

Quote Originally Posted by George1992 View Post
Can I also say "Я иду" when expressing future with "going to"? Like -> I am going to go shopping in a while".
Yes, it' OK.
"Я скоро иду за покупками".

Quote Originally Posted by George1992 View Post
By the way, how do you say in a while and "now" in Russian?
"in a little while" -> "скоро"
"now" -> "сейчас".