1. "limdu" is a verb in the past tense, third person plural. 2. "avur" is used with either nouns or pronouns, and when it is used with a pronoun it must be conjugated. We don't use it with verbs (as opposed to "bishvil"). A couple of examples: .המכתב הזה עבורך This letter is for you. התשלומים האלה הם עבור החודשים האחרונים These payments are for the last months. איזו means "which" (female singular) but we often use it also in the sense of "what kind of". It's במילה because you have the verb "to use - lehishtamesh", which in Hebrew is followed by the preposition "ב": אני משתמש במחשב. I use a computer. זו is synonymous with זאת.

Thanks, Miri :)

just to add something for the עבור - it could be read (since you don't have nikud) as avor (instead of avoor) and then it's a different word. Avor is a command word pass!! - like a guard telling you: pass when you're standing in line... עבור, לך קדימה...