I have 3 DCs and have tended to stay in self catering, but that is what we had free access to. I would microwave sterilise where I could using bags. You can buy cold water sterilising bags that last a day each, our cousin favoured these. I think Milton make them.
I have always given mine bottled water if boiled tap water wasn't available, but I have never boiled bottled water, to me that seems like overkill. We have been to mainland Spain, Greece and France with the kids.
I have always fed my children from our plates in restaurants when small, but I would avoid obviously salty dishes. Lots of salad; yoghurt and eggs are always a good choice from a breakfast buffet, or croissants.
My DCs aren't fair skinned, but in Spain and Greece I have gone for not too much time outside in the middle of the day and good sunscreen. Nivea do one, I think it's called swim and play that is really water resistant. One time ours spent too long in the pool and the cream came off so I swapped to the Nivea one.
I insist on hats, t-shirts while walking around. Only the youngest has ever worn a sun suit because I don't like them, but she thinks he can keep up with DS and DD1 so this was a compromise.
One more thing, I don't know if you are strict about routine/bedtimes, we aren't and the children always come out with us at night and siesta in the afternoon, this is how the Spanish families do it, the children are always welcomed in restaurants and pushchairs too.