That's a huge collection there. I haven't heard all of them -- I imagine few people have -- but for what it's worth:
1. A "salve" is a cream you put on an injury or similar as part of a cure or palliative. Different kinds of problem each require a different cream. In the same way, different problems each require a different solution; there's no one solution that will work in every case.
3. This means you should treat people the way you want to be treated. If you want to be treated kindly, you should treat other people kindly. If you are unkind to other people, they will be unkind to you. (I actually thought this came from the Bible, but I can't find it.)
5. When the Roman Army advanced, their commanders would burn the bridges they had just crossed in order to prevent the troops from deserting. Because they couldn't run back home, they had to stay and fight. If they burnt the bridges before they crossed them, they wouldn't have been able to attack at all. In other words: don't put unnecessary obstacles in your way that will prevent you from achieving your goal.
6. This comes from the same piece of history. Here, it means you should always leave yourself the chance of retreating. Don't commit yourself to something so fully, that you can't back out if things start to go wrong.
14. This sounds like one of those pearls of Oriental wisdom. Doubt leads to questions, questions lead to knowledge. If you are told something incredible, it's probably best to be a little skeptical and try to find out for yourself what the truth is, instead of just accepting it as truth.
15. In other words: Don't eat when you're not hungry and don't drink when you're not dry (i.e. thirsty). Or: Don't be greedy. We all need food and drink, but only enough to keep us healthy -- no more. Also, of course, if we are hungry and thirsty, then we should eat and drink, otherwise we could make ourselves ill. So: take what you need, when you need it -- no more, and no less.
17. Everyone has a bit of luck sometimes. If you play the lottery every week, you might just get lucky.
22. Used to describe wonderful words that are not backed up by action. You might say this of most politicians -- their speeches may be very impressive, but speeches don't achieve anything useful.
25. This isn't a proverb. It comes from The Hitchhiker's Guide to the Galaxiy, in which the story is told of a super-intelligent race of beings who build a computer called Deep Thought to calculate the answer to the "ultimate question of life, the universe and everything". After millions of years, Deep Thought finally announces the result: 42. The descendents of its creators are obviously disappointed, and Deep Thought has to point out that they don't understand the answer because they don't know what the question is -- and then it designs a much bigger computer to find out the question. The writer, Douglas Adams, admitted that there was no significance at all in his choice of number -- it was just random -- but this number has become quite famous.