Unfortunately this is not my house.  My house could have similar aesthetic appeal but needs some work.

How do you do a roof like this?  With a jetpack?  

W Baker

You're gonna have to tie off from the peak/crown.  Or set up laddered cleats drilled into your decking to the left or right of your new work.  And move them as work progresses. It ain't a two man job.  That's at least three….If I were doing it, I would set up at least two sets of scaffolding.  Have one fellow on it with the new tin.  And two roofers.  One works the upper three or four cleats, the other the bottom ones. 

Don't buy and sell scaffolding – buy and keep.  Some of the most invaluable stuff around the place imho.  Heavy duty walk boards are invaluable if you're laying block or brick as mortar boards.  A quadruple stack up to a dormer for painting.  Can't be beaten.Go on Craigslist or Facebook marketplace and buy 'em cheap.  Make sure you have at least four screw jacks as well.

Warren G

If you are doing standing seam metal (fully hidden fasteners) the roofing company will fab the lengths on site. With that steep of a pitch plus the dormer valleys it will be a challenge to get it perfect, and to not die in the process. Hire it out!

There is a whole separate terminology to building and roofing.  On your shed they used standard metal sheets that have exposed fasteners.  Nothing wrong with it, works and lasts well.  I lay out my fasteners to be symmetrical when I install it – just looks cleaner.  In our last build we are currently in, we used a number of different metals/finishes.  Standing seam on the roof is the best (and most expensive).  The bring a big machine to the property with a giant roll of metal in the colour you want and they literally form the lengths on-site and install as they make the pieces.  Very nice finish and lasts decades. 

Note about walls:  We used a (new to me) product on the walls which gives a very nice finish as well. It's called snap-lock and it comes in 12" wide pieces that you order to length. The fasteners are on one of the ribs and the next piece snaps over it hiding the screws.  Gives a standing seam type look but can be done without the fancy equipment. I believe it can be used on roof as well for your project.   Around windows etc can be 1 man job, just slow going. Lots of cutting. If you’re doing a lot of metal work buy a Milwaukee circular saw that’s made for metal. They work well

Emil B

My buddy is a general contractor/ remodel guy. Been working for/ with him for over 20 years. I used him for the roof on my house and my shop. He hates metal roofs with a passion because if they get damaged let's say by a falling tree branch or something your fucked. You have to tear off from the damaged point back and replace and the new stuff won't match because of weathering. But if it never gets damaged it will last a very very long time.

Warren G is correct hire the best roofer you can afford to pull that off don't try it yourself. Where as asphalt shingles can be patched back together if something happens. I used Malarkey shingles on my pole barn and they seem much more durable than the land mark ones I put on my house but both carry a 25 year warranty. Roofing is one of those jobs that is so god damn shitty I'd really really rather hire it out which brings me to my buddy. He has a relationship with a roofer which he has vetted.  He's constantly feeding him work so there's a pretty strong incentive for this guy not to screw up or do something shady. When he did my house roof that guy started to put on shitty felt paper and my buddy says "hey get that shit off my job, use the good titanium stuff like on the other projects"

Titanium PSU-30 Peel/Stick Synthetic Roofing Underlayment, Ice and Water Shield Grade, High Temperature. 3 x 72 ft. Roll (~ 2 Square). Price/Roll.

It's more about where the fasteners penetrate as much as longevity.  That titanium stuff will 'seal' around a nail or screw as opposed to felt.