Mendeh

First, be very careful about the translations you've been given, because the older they are, the less reliable they are. Some of the earliest translators (if Marduck turns up, he'll be able to tell you all about the perils of Budge) produced translations that are simply not accurate. Our understanding of Egyptian grammar and vocabulary has come on in leaps and bounds, so always try to get the newest translations possible. I say this especially with regard to references about 'asiatic slaves' and 'seed'.

3:
The word "aamu" in Eyptian is usually translated by scholars as "asiatics". There are indeed some references in Egpytian writings to asiatic teams of workers (NOT slaves), I believe, and indeed we know that Egypt received immigration from the lands around it, including Palestine. It is therefore possible that the Israelites of the old testament did indeed spend some time in Egypt. However, not all asiatics are the children of Israel, and the Egyptians had another word for Israelites: the 'apiru'.

The Egyptians weren't all that big on slavery, actually, and the picture you get from the stonking Charlton Heston epics like The Ten Commandments just isn't accurate. Prisoners of war would often be enslaved, and usually would be sent to work down mines, which were pretty hellish places.
Archaeologically speaking, the evidence that we have of asiatics in Egypt comes from a city known as Avaris, which was for a period the Hyksos capital. There is nothing to suggest that those living in Avaris were slaves, however.

Another interesting point that suggests Ramesses the Great could have been the Pharaoh talked about in Exodus ("Shishak", I think in the bible) is that one of Ramesses's 'nicknames' was s-s. The Ancient Egyptian language was unpointed, meaning that vowels were not written, so it's possible that the name coming from the bible today is an approximation of how one of Ramesses names was pronounced.

1:
"Israel is desolate." Every few years, the Egyptian army would go out and knock ten bails of stuffing out of all the tribes around them, to encourage them not to rise up against Egypt. Secondly, the oft-repeated image of a pharaoh smiting foreigners was highly symbolic, showing the triumph of order over the primeval chaos, harking back to the creation in Egyptian religion.
Unfortunately, Egyptian records aren't always that accurate. For example, in one of the many battles of Egypt against their best enemies, the Hittites, both sides claim to have won the battle. We have a lot of propaganda from Egypt in the form of stelae and tomb reliefs, and it would be a mistake to be too credulous of their claims.
In short then, you should be a little suspicious of (1), because
- Egypt would go and bash up its neighbours on a regular basis. You can't be sure that this source refers to the events in Exodus.
- The propaganda would usually claim a smashing victory for the Egyptians anyway. This means that you can't take such claims of wanton destruction completely credulously without additional evidence to back it up.
- Egyptian art and writings, especially on tomb / temple walls and stelae, often serve a symbolic purpose as well as a historical one, and beating up foreigners does have symbolic connotations.

I'll look through my books for something about (2) and get back to you if I find anything.