API.Friends.Client.RequestUserInformation(user, getNameOnly). You should avoid doing this if possible, in most cases there is no reason to get a user's information for a user that the local user does not "know".
API.Friends.Client.GetFriendGamePlayed(user.cSteamId, out results). This returns rather or not the user is in a game and if so the results will be populated with information about that game.
API.Friends.Client.GetFriendAvatar(user.cSteamId). This starts the process of loading the avatar image from Steam cashe if its not already loaded into memory.