Hi Bean, I grew up in a church community with a semi-Calvinist tradition. It wasn't until recently when I took some theology courses in college that I fully came to terms with Calvinism and what it's all about. I also struggled for a LONG time about the concept of predestination, or being "chosen". I discovered the problem with this idea was that popular "Calvinist" beliefs and true Calvinism (as in, the sermons and writings of John Calvin himself) treat this issue very differently.
Modern Calvinism is often summed up using TULIP, which is an acronym for the five "important" points, total depravity, unconditional election, limited atonement, irresistable grace, and perserverence of the saints. The problem with this is that it places WAY too much emphesis on the idea of being saved, or "elect", when in truth, John Calvin devoted little time and space to this concept. I remember my professor saying the first time he mentions the idea of election is towards the back of one of his writings, after a member of his church asked why some people never go to church.
The point is, Calvin never devoted important books or other works to this idea and for him, predestination was more of something that HAD to be true because the whole point of Calvin's theology is that we cannot through our own knowledge and our own good works earn our way into Heaven and also that God as the supreme, omnipotent being, has total control over everything. These two conditions being true means the only logical conclusion is that IF God so feels like it, THEN he CAN predetermine who goes to Heaven and who doesn't. But this idea is merely an afterthought compared to the beef of Calvin's theology. People who don't understand Calvinism think that Calvinists have this holier than thou attitude b/c we think we were chosen before birth and everyone else will automatically be sent to hell. This just isn't how it works. Since we cannot know how God works, what He thinks, what method He uses for judging people, we're encouraged not to focus on being chosen, but helping others and emulating Christ. To me, Calvin's theology as a whole, whether one accepts it or not, has NO loopholes because EVERYTHING he taught and believed focused on God's supreme power and man's acceptance of God's grace through Christ. You simply can't believe that God is all-powerful and still believe that if YOU do enough good works or are a good enough person, you can get yourself into Heaven. That's really all you need to know regarding the idea of predestination.
As for freedom of the will, again, here it's only logical that if you believe God is in total control, you have to believe that YOU may not have total freedom. On this issue, I agree with Jonathan Edwards, and I think Calvin would too. Edwards maintained that there is a difference between "freedom" and "freedom of the will". From the wikipedia, "Edwards believed that indeterminism was incompatible with our dependence on God and hence with his sovereignty. He reasoned that if our responses to God's grace are contra-causally free, then our salvation depends partly on us and therefore God's sovereignty isn't 'absolute and universal.'" Everyone has the freedom, granted by God, to live their lives and make their own decisions everyday, no matter how small or how consequential. "Freedom of the will" focuses on the "will" as something, some desire inside of every human being. The will is like what we are most focused on, how we define ourselves, what we want to become, etc. For some people, that is to be like Christ, for others, it might be to be the richest man on earth. Edwards says we don't choose our will, it's just there inside of you and will eventually manifest itself.