Why don't know try a few shorter tours first? It would probably lead to a much more enjoyable longer tour. I agree with others that you need to do some research on touring. As to a few of your questions:

Don't try this without a map! Depending on the country, you want to stay away from major highways and enjoy less traveled roadways.

Although a young man (you sound like one) can probably travel up to 150 k/day on flat terrain, that's an extremely full day of riding and doesn't allow for much sightseeing or anything else. Many tourists would figure something like 80-100 k/day as plenty of traveling, and allowing for seeing something along with way. Lots of touring cyclists travel less per day.

Equipment varies, and you can buy cheap stuff. Even so, I think you'd need a couple thousand US dollars, not including purchase of a bike.

A nice touring bike could easily cost you US$2000, but you could get a passable hybrid for a few hundred.

With camping gear, I would try to keep under 25 kilos. For credit card touring (no camping) we try to keep under 12 kilos. Not always successful however!

Good luck!