Welcome Aboard :)
About stings, sure they have pain involved - you need to know your limit of stings too, it's common to build tolerence after enough stings, but much of it is doing your best to NOT disrupt the hive more than necessary and to dress with confidence.
As your friend does, many of us are in shorts and a teeshirt (I don't do flip-flops) but I don't know how good an idea that is anyway.
I did two full seasons of beesting therapy on my neck which got hurt in a very bad fall: I grabbed workers on their way out of the hive using tweasers by their head (quick and painless) and touched the abdomin on my neck, the sting reflex gets you stung every time that way. I was between 30 to 40 bees at a time, but my point is, that when you sting yourself on each side of the neck, all the stings in the middle make very little pain increase difference. Honestly, 40 felt no worse that 2 - of course THAT is all in one area, you don't want to spead that around cause it sure would ouch a lot, and all the many pressure points and tender spots are a real bugger, but being JUST ANOTHER BEE in your bee yard is a good way to think of being a hobbyist.
The bees have their jobs to and you have yours, confidence is a magical force that really carries over similar to how to handle an occurance with a strange dog. If you are not confident or scared, the bees will know it - and I always like to say, make sure that you are setup for whatever it is you are going to do with your hive, a good example is to have a place to place hive boxes down BEFORE you lift them up - simple things make a huge difference. Your prep time makes any thing you do with the bees better for both of you.
Welcome aboard again, enjoy the forum and great beekeeping.