Is PHP an easy language to learn?

yes. You really can learn the basics of PHP in 24 hours. PHP provides an enormous wealth of functions that allow you to do things for which you would have to write custom code in other languages.

I have heard that PHP was originally developed for use in the banking industry

No it is not true, PHP was originally developed for Web publishing.

How much does PHP cost?

PHP costs nothing at all.

How to know that PHP is there on the server?

Create a page, and upload it on the server, with the following content:
<?php
phpinfo();
?>
Give the .php extension to the page.
The code causes information about our PHP installation to be output to the browser. The phpinfo() function is very useful for debugging scripts because of the contextual information it provides.

Which are the best start and end tags to use in PHP?

It is largely a matter of preference. For the sake of portability, the standard tags (<?php and ?>) are probably the safest choice. Short tags are enabled by default and have the virtue of brevity, but to promote portability, it might be safest to avoid them.

Which editors should I avoid when creating PHP code?

Do not use word processors that format text for printing (such as Word or OpenOffice). Even if you save files created using this type of editor in plain text format, hidden characters can creep into your code.

When should I comment my PHP code?

This is a matter of preference. Some short scripts will be self-explanatory to you, even after a long interval. For scripts of any length or complexity, you should comment your code. This will save you time and frustration in the long run

What are you using to output a string to the browser?

We would usually use print() to write to the browser, although we could use echo() with the same results

I think there is no use of data types in PHP as the PHP is a loosely type language.

It is true that the PHP is loosely typed, which means it calculates data types as data is assigned to each variable. But, this gives a mixed blessing. On the one hand, it means that variables can be used flexibly, holding a string at one point and an integer at another. On the other hand, this can lead to problems in larger scripts if you expect a variable to hold one data type when, in fact, it holds something completely different. You might have created code designed to work with an array variable, for example. If the variable in question contains a number value instead, errors might occur when the code attempts to perform array-specific operations on the variable.