a) What is the Issuance Time?
I assume you mean how long does it take to obtain and install a certificate. It does depend slightly on the method used ( http / dns ) and on the number of domains on a certificate. For me I’d say it’s typically under 1 minute.
b) Is there any browser that do not recognize ssl certificates?
Generally all browsers recognise LE certificates ( I assume the questions was about LE certs not just ssl certs in general) - see FAQs
c) What is the Underwritten warranty?
as far as I’m aware there isn’t an underwritten warranty. It sounds as if you want a free certificate plus them to pay you if you mess up something on the install !
d) Does it has Strong SGC Security? and IP Address Support?
Server-Gated Cryptography (SGC), is a defunct mechanism that was used to step up from 40-bit or 56-bit to 128-bit cipher suites with SSL. I wouldn’t suggest using anything so low in security.
Certificates are not issued for IP addresses, only domain names.
e)Does it Activates green address bar?
Yes the padlock goes green (assuming you have a browser that does so of course) if you have the rest of the configuration correct
f) Is it Mobile Device Compatibility?
I’m not sure how this question is different to Browser compatibility. The general answer is Yes ( again see the FAQ’s and other documentation for the detail of some of the older browsers on different devices)
g) Does it Activates Browser Padlock?
I’m not sure what you mean on this different to your question e) - yes you get a padlock, that’s green if you have the rest of your configuration correct. Have a look at the certificate on https://serverco.com/ if you want to look at the browser response to a typical user installed certificate.
h) Does it works on all shopping cart software? and does it works on works on both www and non-www domains?
The first part here is more a question for shopping carts than the certificate. If the shoppinng cart works with standard SSL certificates then Yes it will work with a LetsEncrypt certificate. And yes, if you configure it for both www and non-www traffic it will work for both.
If you want an independent assessment of an SSL installed on one of my domains to my standard configs, see https://www.ssllabs.com/ssltest/analyze.html?d=serverco.com