1. Actually, many people are saying that leaving the EU will solve many problems, terrorism being just one of them. When people say they want to "take control of our borders" that's exactly what they mean. If they don't, then they are probably being racist, not wanting any foreigners to come in. As for your very loaded question, I'm going to ignore that, because that's not what I'm saying. I'm saying that people who thing leaving the EU will make any difference doesn't know what they are talking about.
2. I've probably answered this already, but to make it clear: If someone is determined to come in - and I think that you can class all terrorists, suicide bombers etc. as 'pretty determined' - then all the border controls in the world won't stop them. Being able to work together with the governments and authorities of the countries they travel through to get here - that will help. Washing our hands of the ability to work across Europe with the intelligence and security forces of twenty eight other nations will do nothing but harm.
3. I'm not contradicting myself. Point to where I said we were not a powerful nation. Actually, point to where I said we were a powerful nation. What I actually said is that we're "the fifth biggest economy in the world" and that we're "not as powerful as you think we are". I never said we were powerful, but we are economically thriving. And I never said we were weak, just not as powerful as you think we are. I think you need to maybe re-read what I'm saying, otherwise your responses will not be as coherent as you want them to be.
Finally, also on point 3, there's yet another rose-tinted view of this situation. If the people of this country are what makes it great, why is leaving the EU so important? Because many of the people in this country, working to keep this country great, are EU citizens.