Gravel build for cycling holiday

Hmmmm...  Regarding the frame/fork:
At 435mm, the chain stays are on the shorter side for a touring bike.  This frame is definitely more of a CX/Gravel setup than touring. The shorter chainstays pull the panniers nearer one's heel. If you have small feet, not a problem.  The shorter wheelbase will be quicker and more lively when commuting or out for fun rides, but will give up some stability under load.  By comparison, check out the geometry of the Salsa Vaya which is a gravel/touring bike - but not an all out touring bike like the Surly Long Haul trucker:
http://salsacycles.com/bikes/vaya/2017_vaya_gx

I definitely prefer the feel of carbon over steel forks, especially on gravel. Looks like the fork has front pannier mounts on the main tubes but no eyelets on the fork near the axle. Might be worth a call to find out if the picture is accurate. Whether or not you decide on front panniers, having the mud guard mounting IMO would be much better than trying to use clamp-on mud guards.

The frame spec says there's clearance for 42mm tires and since you're planning on riding in rain I expect there will be ample mud.  I'd suggest checking on the largest recommended tire when using mud guards - I would expect a 38c tire would be the widest but for extra clearance for mud you may want to use 35's. Instead of having the mud guard follow the tire perfectly for the best aesthetics, for safety I leave a bit extra room between the tire and mudguard near the ground. This results in the mudguard being a bit closer where the tire exits at the top, but hopefully will avoid mud on the front tire from causing the mud guard from collapsing. 

Tires/Tyres: I have used several of the Clement gravel and CX tires and love them. They are light and ride great -BUT- for durability and flat protection they're no match for my Schwalbe Marathon Mondials (formerly the Marathon XR).  You can't have light supple race tires AND the long wearing and flat/cut resistance of the Marathons.  

Shoes: This depends upon how much riding and walking you do.  I've got Crankbrothers pedals on all my bikes except my one road race bike. The larger platform of the Crankbrother Candy and Mallot pedals help spread pressure and avoid hot spots.  High end mtb shoes are very stiff and one can ride 100+ miles even with the small eggbeater (or SPD) pedals because the rigid sole provides a wide platform for the foot. Less expensive shoes are more flexible which makes walking easier but are more likely to cause hot spots if one is spending long days in the saddle.  If I were planning long days of riding with a more flexible soled shoe, I'd definitely opt for a pedal with a larger platform.  FWIW I've had good luck with Sidi, Northwave, Specialized and Carnac shoes - but I always check to make sure the sole is rigid.  Of course the usual disclaimer on footwear applies: brands which fit my foot might not work well for you.  Cleats on mountain shoes are not an issue as they are recessed, but the rigid soles can be awkward so I'd expect you'd want a 2nd pair of shoes or sandals.

Lights: If you don't want to worry about recharging batteries, then a dyno hub and LED light is excellent -BUT- a good setup is going to set you back quite a bit.  My preference in lighting is for the LightAndMotion Vis360+ on my helmet and a second headlight and taillight mounted on the bike. I especially like the ability to point the headlight at vehicles or in the direction I am looking - as opposed to the handlebar light which points straight ahead.  So many options on lights and different preferences (religions?).  For a two light system I prefer a narrow beam and wide beam.  The Vis360 is a wider beam so my preferred handlebar light is a narrower beam.   To pick an ideal headlight (or combo) consider how fast you'll be moving, the road/trail surface, and duration.  My preferred USB headlights are 700 to 800 lumens with a 2 to 3 hour run time.  When riding slow to moderate I'll have the light on the low setting and then will switch to high for fast descents or more technical situations.  For a second taillight, IMO the Cygolite Hotshot can't be beat.  Rugged, relatively inexpensive, USB charging and long lasting.  Note that within a product line, the most expensive and brightest model frequently has the same run time as less expensive models because of the LED being used.  
Cygolite Hotshot:
https://www.rei.com/search.html?q=cygolite+hotshot&ir=q%3Acygolite+hotshot&page=1

Vis360:
https://www.rei.com/product/853295/light-motion-vis-360-plus-helmet-light

There are lots of other much less expensive lights for being seen at night, but the Hotshot 100 and 150 will even make one visible during the day.

Mudguards:  Planet Bike makes some nice 45mm mudguards at a reasonable price, but they may need some grinding to fit your bike:
http://www.chainreaction.com/product/planet-bike-cascadia-fenders-hybrid-touring-81217-1.htm

For more info and other product offerings check out these vendors which all have lots of useful info and some excellent products and hard to find parts and accessories which could be useful:

Peter White Cycles - lots of info on tires, fenders, lights and much more:
http://www.peterwhitecycles.com/fenders.php

Velo Orange:
http://store.velo-orange.com/index.php/accessories/fenders/700c.html

One last source - Rivendell Bicycle Works has lots of info and quality products on their web site:
https://www.rivbike.com/collections/accessories?page=2

Happy shopping!
Greg

BTW - here's a link to the Schwalbe tires I was referring to. Schwalbe has a very broad line of trekking/touring tires. I have only used the Marathon XR's and Mondial DD's:
http://www.bike-discount.de/en/buy/schwalbe-marathon-mondial-dd-travelstar-37-622-folding-482345?currency=5&delivery_country=191

FWIW, I have 2k+ miles of commuting and general riding on gravel and paved roads on a set of 40c (42-622) folding DD's.  When commuting I typically had 25 pounds in the back panniers - about 260 pounds for a total load (me+bike+stuff). The rear tire is showing signs of wear but still has a lot of tread life and the front appears almost new.  No flats with these tires. I purchased these to replace some Conti's after my third flat on an early morning commute.

Thanks Greg,
that's already a bunch of useful answers !