ride with what's comfortable. If lycra makes it more comfortable for you, wear it. If you feel like you need water, bring it. I never understood the crowd that says "you shouldn't wear bike stuff if your ride is less than X". I wear compression shorts for my 6 mile commute - sure changing is a hassle, and there are likely other options I have yet to explore, but it makes a difference for me so I wear it. Blanket statements about things such as comfort just don't work

I try to bring water with me every time I go out for a ride, even if I'm on the trail and there are water fountains every mile or so. It always is a "just in case" supply, and I know that if I have it I'll drink it at some point, even if its at work