Flood

Let's see if I can answer your questions. Remember, this is pure speculation since the Bible doesn't tell us one way or the other on this.

It's likely that all the animals were in some sort of hibernation mode. They obviously showed up to board the ark on God's command, and the Bible says that God (or an angel, I can't remember at the moment) closed the door of the ark and sealed it, so there were some very obvious miracles happening. It seems pretty reasonable to assume that God made sure that the animals didn't kill each other (or the humans) while they were trapped in a boat. They might have entered individual cages to keep everything seperate that ate meat too. God commanded Noah to bring extra animals of the species that people could eat, but He didn't make similar provisions for the animals, so I'm going to go with the idea that they simply didn't need to. This also answers how termites were able to be there - like other animals, they simply waited out the Flood.

Salty or fresh water? Well, let me give you a bigger picture answer for this one. Young Earth Creationist believe that our current Earth isn't the same as the one from before Noah's ark. Different in serious ways that science has no way of proving (because science has to start with the assumption that what we have no is the way it has always been). For example, the Bible states that it had never rained before the Flood - apparently there was 'water from the ground' (lots of springs? Mist? Dew? I have  no idea). God changed the water-cycle of our planet at the time of the Flood so that now rain is a completely natural phenomena. So natural that we can't figure out how it would work differently.

We also would assume that the Flood brought about other huge, catestrophic changes - things that are still being felt today (such as earthquakes, volcanos, hurricanes, etc.). These are events that would not have ever existed in a 'perfect world' like the Garden of Eden, but were likely started when God re-shaped the Earth during the Flood. The geography of Earth was re-formed (probably causing the land-masses to split apart into the continents we know today). All sorts of consequences! Evolutionists see a lof the same geological events that YE Creationists do, but Evolutionists claim that they took a long time to reach the point that they are today (like the idea that it took millions of years for the American continents to split off from Europe and Asia and create the Atlantic Ocean) whereas YE Creationists would say that it happened quickly. Same event, just a different time-line.

So we have some things that were 'natural' events (like dividing continents) and others that were 'miraculous' events (like creating a water cycle). Okay, let's look at a couple of other things that the Bible says. First, in the New Earth, we know that the animals will return to their Eden-habits of eating only plants, not other animals. The Bible says that the Lion will eat straw like an ox, that a wolf will lay down beside a sheep, that a person can stick their hand in the nest of an asp and not get hurt. So at some point, either when humans first sinned, or while God was doing other major changes to the Earth during the Flood, God re-formed animals, making some of them carnivores. This gives precedence to the idea that God has changed the nature of animals at least once already. On top of this, in Revelation, the Bible says that along with 'no more pain, no more sorrow, no more darkness', there is also 'no more sea'. That's kind of a random thing to have 'no more of', isn't it? Well, there's two possible reasons for this - one is that the ocean has historically been a source of fear and danger for humans. It's only recently that people have found ways to safely travel across the ocean, after all! So a New Earth without a sea would have been a very positive thing for most of the history of humanity. But there's a second possibility for this and it goes back to the idea of salty vs. fresh water. Salt water is posionous to humans and most animals. So it seems  possible that all the bodies of water will become fresh water in the New Earth. This would mean that there wouldn't be 'seas', but in a different way. If this is true, than it is possible that originally all waters were fresh waters until the Flood, at which point, like making carniverious animals, God changed the fish and mammals in those bodies of water to be able to handle the situation.

So my answer to 'Fresh or salty' during the Flood was...both, sort of. God had a direct hand in forming the Earth once the Flood was over and I think he made sure that the fish (and other aquadic life) ended up in the proper locations and with the proper biological equipment to handle the situation once it was all over.

Okay, since we've been talking about the Flood, let me point out what 'lesson for us today' exists in this story. What spiritual truth is a person supposed to learn from the story of Noah and the ark?
The lessons are: God takes care of His people. He always provides a way of escape for those who trust Him. But that way of escape may not always be fun.
It wasn't fun for Noah (imagine spending a hundred years building a boat on dry land when no one has ever seen rain before. How much do you think the people around Noah laughed at him? I'm betting a whole lot! But he dodgedly persisted and his faith was rewarded. He was saved. And his family with him. The ark was probably not much fun either (smelly, dark, and in constant motion), which is probably a metaphor for life in general, but he made it out to the other side to reach 'the promised land'.

Okay, well, I'll have you either read the story in Genesis of Noah's ark (Genesis), or, if you read this recently (which I kind of think you did), read this instead:   It doesn't have anything to do with the discussion at hand, except to point out how God will always be there for us - and nothing can stop that fact.