How long is the trek? How is the trek route like? Do I need a guide? Is there any Medical Aid available?
Gaurikund - Rambara Bridge - Jungle Chatti - Lancholi - Base Camp - Kedarnath (16 km)
It is a well laid out trek all the way through, paved and pretty straight forward.
From Gaurikund to Rambara Bridge (about 7 km) it is gradual yet easy ascent.
It is a steep, gradual ascent after crossing the bridge at Rambara, all the way to the base camp, where it flattens. The last 1 km or so is an easy walk to the temple.
You do not need a guide. Horses, Mules, Palanquins, and Porters are available at Gaurikund. It's better to book them at Gaurikund itself; you will find many at several points on trek too but they will ask for a price higher than the altitude you will be standing at.
Medical and First Aid facilities are available at several places including Lancholi and Base Camp. There even is a small government hospital just 200 metres from the temple. And police check posts on several points.