Tire pressure and changing flats

[steveyo]

I have a technical question for you.

My tire on my KH29 had about 60 lbs pressure in it all winter and spring without losing any pressure. My last ride was a long trail ride 3 days ago, then yesterday I went to ride and the tire had NO air at all. I pumped it back up and it seems to hold the air, but I don't trust it.

Questions:
1: Since it went so flat so abruptly, there must a leak in the tube, right?

2: To change the tube, I need to remove the entire wheel, right?

3: To do this I just need to remove the bottom brackets, right?

4: Is there a special tube I need, or just a 29 in (700c) bike tire tube?

5: Will changing tube or tire be any more difficult than changing one on a mtn bike?

Thanks,

Steveyo