Is Crush slider really free?

Yes; for personal use which means Blogger version is always free.

What is the efferent between free & commercial version?

The free version is suitable for personal blogger address, like
Commercial version is suitable for websites and blogs those use custom domain. Eg:

I have a business related blog but my blog doesn't uses custom domain. It uses the default url like Should I have to buy a commercial licence?

No, you don't need to buy anything, You can use Crush slider fro free.

I have a 100% personal google blogger. Its painting related, but uses custom domain. Is Crush slider free for this kind of blog?

Because you are using a custom domain, so it need a commercial license. But don't worry its only one time charge.

I want to implement Crush slider in a website; is it possible? Should I need a commercial licence for that ?

Yes, definitely you can implement this plugin in a website. Yes you need a commercial license for that.

I am just a regular blogger user, don't know HTML or coding, how could I implement Crush slider in my blog? 

You can use the embed code by using copy & paste method. There are plenty of easy video tutorials available in Youtube on "how to embed HTML code in blogger".

I think I need a commercial Licence, just a pre sales question; I need to confirm whether its a one time charge or there are any kind of renewal charges?

It is one time charge. There is no renewal or any other kind of charges at all. But please note: the commercial licence is set by 1-Licence for 1-domain. If you ever need crush Slider for another domain, you need to purchase a separate license for that particular domain.

I have downloaded Crush Slider. Before upload it to web, I have tried to run Crush Slider locally in my PC. But its not working, showing blank.

While running Crush slider locally (in your PC), 
  1. Do no change the name of the Mother folder.
  2. Keep the mother folder in you Desktop.
  3. Its recommendation to use HTTPs rather than HTTP. Eg:
If none of the above mentioned solutions doesn't solve the problem, test with a different blog address or you can test with this demo blog address: If the demo blog works and your blog address does not, it means there is a problem & Crush slider wouldn't work in your blog. Please note: Crush slider doesn't works for some blogger. The reason is still unknown. We have tested this slider with many different blogs and 4 out of 50 blogs didn't work. Please test this plugin with your own blog before purchasing or any serious project. We will try to resolve this issue later.

Performance issue; Crush slider taking approximately 14 to 20 seconds to load, how to improve this?

Solving this problem permanently You need to host all CSS, Javascript & Jquery files somewhere else. If you have installed Crush slider by Embed code method; you may face this kind of performance issue because, already a lot of user using Crush slider from the embed code, so the server simple not capable of handling the bulk user load. It eats up a quite significant amount of memory. Currently served traffic is 100+ GB for October2017. So use your own file & you would get a smooth performance.

Where can I host all those CSS, Javascript & Jquery files?

You can host those files in these below mentioned free & paid hosting platform:

List of Free hosting platform:
Alternatively there are some paid options available too like Godaddy, Bluehost etc.

Can I host all source file (CSS, Javascript & Jquery) files in Blogger itself; as I have seen in a Youtube video tutorial that its possible?

Partially yes.... You can host only the CSS code in Blogger, but most of the Javascript & Jquery files in Crush slider are Library file and you may face problem to run those library files from Blogger.

Can I use Crush slider as a Google Gadget?

Yes you can convert this plugin as a Google gadget & use it.

Can I use Crush slider as Google App Script (WEB APP) ?

No this plugin isn't suitable for Google App Script.