Hi, I'm just trying to get some advice on this route in June, as I'm a bit confused about the price. If you take a look at the picture:



You can see that for some reason on the 4th of June, this route is a lot more expensive on Vueling than other days. My questions are:

(1) Do prices for flights fluctuate heavily for routes like these? I.e., should I just wait to see if this price drops. I could potentially fly on the 5th, but 4th is most preferred.
(2) How is Vueling for a route like this? I saw some FT posts of horror stories though also posts that basically said 'it's fine.'
(3) Does Vueling allow a carry-on AND something like a backpack without cost? This will be my first time in Europe and I'm somewhat baffled by the baggage policy of the various European carriers (e.g. RyanAir, Easyjet, etc.)

Any thoughts about the above would be greatly appreciated, thanks.