Hi Dario, welcome!
As I don’t play dwarves myself (but face them regulary) this reply will be more from a modellers perspective than a gamers’. This means that the aim is to have it look good instead of fielding only the most effective army. (which IMHO is more important than getting the most effective unit on the battlefield)
As for multibasing: I generally aim for ~8 models per troop (sometimes abreviated to PMC or Preferred Model Count) so that’s what I’ll be going for.
so going per model:
24x Thunderers (=> Ironwatch rifles, or perhaps Sharpshooters with some conversion work?)
I’d go for ironwatch, since this is the logical conversion to KoW. While these can make 3 troops, I wouldn’t do so. Ironwatch rifles are not up to scratch this edition (or the previous one, for that matter), and while the Rules Committee has promised to buff them, I don’t have the information how and what. I would build 16 of them into a regiment (or 2 troops) and use the remaining 8 as 2 troops of sharpshooters. As Sharpshooters are long-barreled rifles with shields, it’s an easy conversion for thunderers. 
22x Warriors 1 handed and shield => Ironclad indeed. They make great anvils. I’d use 16 for a regiment and keep the rest for conversions / unit fillers. Separate any banners you might have for an army standard bearer, as these are always useful.
14x Warriors 2 handed => Shieldbreakers. Just add 2 of the warriors and make it a regiment. (rip off the shields and do a weapon switch. or just use the musician/champion)
25x Miners => These have no direct counterpart in Kings of War, which means you can choose what to do with them. You might want to mix them between the 2-handed weapon warriors and go for a horde of shieldbreakers. The increased nerve does much to aleviate the decreased defense and 25 attacks with crushing strength is nothing to scoff at.
1x Cannon with servants => A cannon. Decent war machine.
1x Thane => Dwarven king. Don’t know if he’s good enough for use, but I see them flying around a lot. (using the wings of honeymaze magical artifact.)
2x Dragon slayer => Berserker lords. While they usually ride brocks when I encounter them, they are killing machines. I’ve also seen the wings on these guys for additional killing power, only their low defense makes them really squishy, so I’ve learned to blast them from the skies early!
10x Stormcast eternals paladins (I’ve read someone uses them as Earth elementals) => this is a good match. They also make great ironguard.
50x Dwarfs with spears EM4 > Bulwarkers, yes! They are quite good this edition, so this is at least a horde. (32 of them make a horde, add 4 warriors with shields for an additional regiment).
As for the buying list, I’d buy at least one regiment of brocks and a king on a large beast. Then depending on the kind of list you’re going to do either:
-a few more war machines
OR
a horde (or two) of earth elementals, probably a greater earth elemental along with a stone priest or two.
These are two kinds of army lists I see on a regular basis. Both feature a core of dwarven infantry (because, duh) supported by some more mobile elements such as brocks, a brock lord and/or a king on a large beast. Then the army features either a couple of war machines or a number of elemental units with stone priests to do surge shenigans. If you want to buy a couple of earth elementals, there’s the Mantic ones. alternatively, Reaper has quite a selection. Mine are reaper too and were quite cheap.
Of the two, I like playing against the elemental list better. Dwarves are always at risk of turning the army into a gunline. Battles with and against a gunline aren’t so much fun and other armies do it better at (looking at you, Goblins and kingdoms of men)
As one of my friends has been trying to start his dwarven army for a few years now (and still not succeeding), I made a tutorial for his brocks. Here’s it, if you’re interested:
greets and good luck,
Vince
