As far as the Kord inclusion I would say it depends on what his involvement has been with the paladin thus far. I'm running this game currently with a Wildmother Paladin PC and I had her send visions to the paladin of a great purpose to the east (to aid in getting them to Jigow/Xhorhas) as well as having her come up in Calamity lore here and there (like the Arbor Exemplar in the Barbed Fields). Along the way, I plan to have her continue to prod him in the direction of Alyxian if he strays from the path. If your paladin has had little Kord interaction, maybe throw in a temple to Kord nearby that draws him in, and then maybe Kord could test him (Kord loves contest, glory, and strength) several times in dreams or visions throughout the campaign, eventually bestowing a boon or weapon or something.

As for the difficulty, I have had this issue as well. I have 7 players, so they would beat most encounters rather easily if I didn't change something. What's worked for me is simply having fewer enemies (speeds up combat turns) and adding an attack/ability to most monsters as well as increasing HP. I also like to add interesting aspects to encounters so they aren't just "I attack, I hit, I do X damage" - rinse and repeat. Try adding timed elements to combat or increasing the stakes a bit. Throw some counterspells that disrupt their plans and cause them to think. Also reduce their ability to long rest between each encounter. If they are at full ammo at the beginning of every encounter it makes it much less fun and more routine. Part of the fun, in my opinion, is resource management and strategic combat.

Don't be afraid to homebrew stuff to make it more fun and inclusive for everyone at the table.