What do you mean by "point" and "aim"? In a literal sense, no they're not pointed at the US. In reality, there may be a ICBM stored that has a set of pre-programmed destination coordinates, which include the US, which also include many other destinations. The US may also have an ICBM stored somewhere with a similar set of pre programmed destination coordinates. Are they a threat to the US? Both countries have agreed that any kind of nuclear warfare would wipe both countries off the planet. Such an event would not be beneficial to either parties interests.
Yes. The USS Cole was really attacked. Theres a big hole on the side of a naval destroyer that confirms this.
What do you mean by secured? Are we keeping tabs on borders? Yes. Is it possible to get some kind of variant of a nuclear warhead, however small, through a border check? Unlikely, but I wouldnt doubt it. Is it feasible or practical to take that kind of route to inflict any kind of damage? Not at all.