there isn't exactly a word in hebrew (as far as I know at least) for thunderbolt so it would be just the literal translation- ברקים ורעמים מאוד מפחידים/מלחיצים אותי. although we don't have a translation for thunderbolt, we have a phrase (expression of anger) - חזיז ורעם (cha-ZIZ) - חזיז literaly mean firecracker, and as a firecracker makes a flash of light in addition to the bang sound, the word been "borrowed" from it's original meaning to describe a thunderbolt (mainly in literature)
You're right. It's the /u/ sound.
Normally, the conjunction "ו" is pronounced simply as "ve". But in some cases its' pronunciation changes. In this case it changes to /u/.
I can give you more detailed and grammatical answer, if you need :)
7 May 2019
In English, lightning and thunder are usually used as uncountable nouns, which can refer to more than one instance. This is the case in this sentence.
In Hebrew they are countable nouns, so you use the plural when referring to them in general, or the singular for a single instance.
nice, I also found the song with tekst:
Well, because light travels faster than sound, a more natural order would be to say lightning and thunder, but it is thought that the idiom was influenced by Ex 19.16 קלת וברקים (literally voices and lightnings) which was translated in the Greek φωναὶ καὶ ἀστραπαὶ, Latin tonitrua ac micare fulgura and the King James version thunders and lightnings in its switched order and became fossilised in this order. For German Blitz und Donner, Yiddish בליץ און דונער and subsequently Hebrew both orders are possible, but f.e. this popular song has the Biblical order, but the caption is the other way round ;-)