I bought Witcher 3 for Switch because I loved the tv show and wanted to support good third party games on the system. 
I'm about 3 hours in but I'm having a hard time with it. It feels really clunky. I am not used to combat yet... Do all weapons and armor break? What happens if they do? I'm on easy difficulty but still having a hard time. 

I love open world games, and I know they take a while to really get into, but I feel like this one has a much steeper learning curve than say Breath of the Wild, or Assassin's Creed.

Any tips/hints would be greatly appreciated :) Thanks in advance!

For starters, go into game options and switch to the movement controls from standard to alternate. It feels much better that way.

Does all your equipment have durability? Yes. Everything will degrade over time. Except probably the crossbows. That said, your armor will only degrade when you're actually taking damage, so once you get better at the game, you won't have to worry about repairing armor all too often. If you're struggling with dodging, Quen is your friend. Swords are going to need pretty regular upkeep though. If any of your equipment degrades to the point of breaking, it's not really a big deal (beyond the obvious protection loss on armors, and the fact that you won't be able to use your swords), it just means they'll need more repairs. Meaning either more money spent at a blacksmith, or more/higher quality repair kits used.

I would recommend a playstyle with a healthy mix of combat and alchemy abilities. Frankly, it's both more fun, and more effective than going too deep into a sign build, which relies almost entirely on spamming everything with Igni all the time. Throw a few points in some complimentary signs if you want, but they'll serve their complimentary purpose just fine even if you don't upgrade them at all, really. Better to spend some time making sure you're getting as many alchemy recipes as possible, as they'll provide very nice buffs for the various enemy types, and increasing your toxicity threshold allows you to have multiple active decoctions, which can really supercharge your combat abilities.

Just hopping in here for the sake of bookmarking as I just happen to be (finally) starting this game myself

A few hours into the game... And there's a lot being thrown at me. I still don't really get what alchemy is all about.

Wow, it seems I'm not the only one! That's a relief! And thanks for the tips!

First playthrough... You're assuming I'm gonna play this game more than I'm likely to lol.

As a general question, I can't seem to get the custom waypoints to work. When I hold X (playing on XBox One) it just brings up a custom marker instead.

just invest everything into Quen, rly the best sign by far in Witcher 3. That is all you need, You will get better weapons and armor throughout the game and Quen will just make it much easier. Also try to look for location for Cat school diagram as soon you can since that is the best Armor(bear is also good if you just like to stand in place and do huge damage)

If I hold X it lets me use different symbols. I figured that a waypoint would be be something that's tracked as an objective on my minimap. Maybe I'm misunderstanding what that means.

Honestly, seeing as its your first time with the game I think you should play straighforward as possible until you familiarize with the more elaborate mechanics, by which I mean go the physical route and dont bother much with alchemy and/or glyphs, except maybe Quen and Igni. Do try to learn quickly how mutations works cause that will boost a lot of your combat prowess.
I guess you could look up where to find witcher gear of certain schools. Its the best and easiest way to equip yourself with good items and having that gear makes using the ones that enemies drop - which are rather weak - irrelevant. Of course you might wanna try them for cosmetic reasons, seeing its your first time playing.

Other than that, save frequently and dont try to romance both Triss and Yen. As you progress the other elements of the game might become more important but I assume you'd already be a bit familiar with how they work.

I think I'm going to have to throw in the towel on this one. The world seems interesting, but so far the story has been "Hey we're looking for this person." Find that person... "Cool found me. But this person's missing." Go to a dude who may know where they are"well, I'll help you find that person... but first, find me these two other people." Go to a person to find more information on them "I'll help you find the person, who will tell you how to find the other person, but first find my goat."

Just not into the pacing here, and the gameplay itself isn't engaging enough to keep me interested.