I say go for it! However don't expect to go vegan and just automatically lose weight. When I first went vegan (though i eat fish once and a while) I ended up eating a lot of things like french fries, oreos, coconut curries, and other way fattening things and i gained some weight. You still need to count your calories. Other than that, it definitely helps with a lot of health problems, reduces your intake of nasty antibiotics and hormones, helps with environmental issues (did you know that cow farts are a leading cause of greenhouse gasses?), and reduces the horrible treatment of animals. I highly reccomend readingEating Animals by Jonathan Safran Foer to learn about some of the non health related reasons for going vegan.
About calcium there a lot of people who argue that milk consumption is actually very bad for your bones. The China study, and others, showed that nations where very little dairy is consumed have lower rates of osteoporosis. This is because the acidity in milk helps to break down bones and the calcium gained isn't enough to replace it. Calcium from veggies is much better for your body. Also its very easy to find things like soy milk, cereals, and orange juice that are enriched with calcium.
As for amino acids, just eat things like beans and rice together or within about 24 of eachother. Beans and carbs in genral do it like hummus and pita or beans in a taco or something like that. Any kind of nut butter and toast, or nuts and oatmeal, Tofu and grains, . So you don't really have to eat these things at the same time, just within the same day.
Plus there are TONS of DELICIOUS vegan recipes out there. One thing though is you need to make some time to cook so that you don't end up eating rice and beans every day.