にゅう
はい, い
None
The kanji and the radical are the same, so remembering the meaning of this kanji is as simple as making sure you know the radical for enter first! If you know the radical, you know this kanji means enter as well.
Turns out, after you enter the teepee (you'll remember that the radical is a teepee with a big entrance to it), you're given a new (にゅう) one! Now you have two teepees!