Q&A

Q1:	Why can it be useful to know the type of data a variable holds?
A1:	Often the data type of a variable constrains what you can do with it. You might want to ensure that a variable contains an integer or a double before using it in a mathematical calculation, for example.
Q2:	Should I obey any conventions when naming variables?
A2:	Your goal should always be to make your code easy to both read and understand. A variable such as $ab 123245 tells you nothing about its role in your script and invites typos. Keep your variable names short and descriptive. A variable named $f is unlikely to mean much to you when you return to your code after a month or so. A variable named $filename, on the other hand, should make more sense.
Q3:	Should I learn the operator precedence table?
A3:	There is no reason why you shouldn't, but I would save the effort for more useful tasks. By using parentheses in your expressions, you can make your code easy to read at the same time as defining your own order of precedence.