@smariej Great question and congrats on your first hike!
@REI-JenK got you covered around the benefits of carrying a bladder, I'm going to speak to the electrolyte question. Typically I'll carry some sort of electrolyte product while I'm out just in case. Most are small enough that they can disappear in my pack and are not inconvenient to carry. I also take a couple extra in case someone I am with is exhibiting symptoms of dehydration. It really depends on the exertion level and distance I'm covering as to whether I personally use it or not. Additionally there are a lot of different options on the market; I recommend trying a couple out to see which one has a flavor you enjoy. I find that if I am in need of electrolytes it can be really challenging to drink the correct amount of liquid if it doesn't taste appealing to me. For me, I enjoy NUUN tablets as they don't rely on a lot of sugar to replenish your electrolytes.
I hope this helps, thanks!