1. t/s are the thiele/small parameters. they are the things such as xmax, vas, qts, pe, q...etc
2. you buy them //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif
3. some yes, some no (the more expensive, the less they are likely to give u a cut sheet, but they will tell u the dimensions)
4. it would be ideal to just have the program do it for you, but if u want to do it by hand, good luck. it would be best to learn the relations using a program before u started it on ur own.