Running

How hard is it going to be and how long will it take me? Also training?

Have you completed any Ultras before?
Depending on Ultra experience you could be looking at 8-10 hours or more/less depending on a number of factors, general fitness,weather, age , hydration, nutrition and elevation experience. The Lap has just over 8,000ft elevation which is reasonable to say the least. Running up and down hills in your training will help you greatly in your overall fitness but there is nothing wrong is walking hills in an Ultra race.

Also Training?
A lot of Ultra plans are 16 weeks , This one looks rather good - some are very complicated (to me anyway) and this one has rest days which are important.
https://www.runnersworld.com/uk/training/ultra/a774983/16-week-50-mile-ultra-marathon-training-schedule/