Regarding capacity, it refers only to the Inca Trail. Depends on the time of year you are going. During the peak season (northern hemisphere's summer) it may be tough to get a spot without reservation months in advance. There is a limit of 200 people per day (or maybe it was 300) starting on the Trail. If you go during the wet (off) season, you could potentially find a tour operator when you arrive in Cusco; but you may also run the risk that the quota has been reached or the tour operator is full that particular day.

The train to Machu Picchu is limited only by the number of seats on the train (and there are multiple trains a day). You could also take a bus if you are so inclined (though it may take much longer and bumpier ride).

Reservations for either the Trail or the Train depend on your travel dates. Peak season you have to book way in advance online or be very flexible (and lucky) to try booking in Cusco. For off season, you can probably book either on arrival but you may risk not getting the day that you want.

The other part that has a limited capacity is at the far end, if you want to climb Waina Pichu, the sacred temple mount at Machu Pichu - it's limited to 400 people a day (from all who enter MP, regardless of Inca Trail or by bus/train), and they have to arrive and start up that trail before noon. Extra charge, of course...

I was there 11/05, there was no charge at that time. You are required to register and write your name in a log, probably so they can go look for you if you fall off the cliff to your death.

I am about to go to Lima/Cuzco/MP in 3 weeks. Can anyone recommend a tour service/guide/company? We found one - SouthAmericanhotels.com, but we know nothing about them.
Any recommendations on specific hotels in Cuzco and Machu Pichu? We plan on staying at DoubleTree in Lima as we are Hilton Diamond. All help would be appreciated. Thanks

The Incas had no written word, and the place was abandoned until the early 20th century. So, no one really knows what you're seeing. I'm a history buff, and I was shocked to hear some of the tall tales the guides tell people...

Enjoy it for what it is, and take good pictures. You can always read up on it (from good serious sources) before or after your trip.

Things may have changed, but back in December 2001, my wife and I paid US$20 each for the R/T backpacker train from Ollanta (AKA Ollantaytambo) to MP. Entry to MP itself was about $20 each. You can get to Ollanta from Cusco in one hour by cab, for about $10 (this last price was current in 2006).

I don't like taking the train all the way from Cusco, because you have to get up at an ungodly hour, plus the train is way too slow when getting out of the Cusco valley. It takes 4 hours to MP. If you take the train from Ollanta, it's only a 90-min train ride.

I think you need more than 10 days and you should be sure to spend a couple days in the Sacred Valley. Also, Lima is worth seeing too. Yes, it'sa big city, but there are sights to see there! Personally, I think if you can stay longer, you should. Peru is a fabulous country to explore. have a great time.