A lot of this comes down to personal preference and how you’ll ride.
I’ve got a bike setup in the UK for road/commute with full mudguards with 2 wheelsets that transforms for loaded touring/bikepacking and chunky gravel - which is really just mud for much of the year.
1x does a fine job for all of these asks but it’s very rare that I try and e.g. ride sustained power intervals on it. Have done some punchy club rides and it does fall short downhill. 40t x 10-51. It works for 99% of how I ride the bike. Note that I also happily ride around fixed gear 
Mudguards: Have PDW metal guards (they do a nice looking plastic version too) and these are the easiest full guards I’ve dealt with for ‘quick’ swaps. Changing the bike from gravel mode back to road with a wheelset swap, guards back on and caliper alignment (for some reason only the rear needs adjusting) can be done in 15 minutes - where 5 minutes is the disc/caliper fiddling 
As for basic suspension, maybe look at redshift stems and redshift or cane creek for seatposts OR get something that runs CX/MTB tyres and see how it feels first. Nearly went for these but the bike now runs 2.1 inch 27.5 mezcals.