- While activating ssl in namecheap, it asks for server type. which include options like "apache2" "apache+openssl" "apache+modssl". Which one should I select ?

iRedMail setup HTTPS with Apache2 + mod_ssl, i don't know which one matches the options. Do it provide more details about these options?

You place purchased SSL certificate under some directory, then update related config files (e.g. Apache config file) to use them. There's no need to delete them, but of course you can delete them if you want - after you have purchased SSL certificate work.

Your SSL certificate provider should public related document about how to generate SSL certificate, and submit one of them for signing. If not, read Apache document instead:
http://httpd.apache.org/docs/2.2/ssl/

My server is up and running all great. Now I want to assign an Comodo Positive SSL bought from namecheap.

- While activating ssl in namecheap, it asks for server type. which include options like "apache2" "apache+openssl" "apache+modssl". Which one should I select ?

- What happens to the ssl certificates installed already by iredmail. Do I need to delete them ?

- My FQDN is mail.example1.com and another virtual domain is mail.example2.com. Will I be able to type in mail.example2.com and land on roundcube without getting a warning ? and subsequently other virtual domains like mail.example3.com which I may add in the future ?

- If there is any step by step guide available which closely matches to what I am looking for, please mention so.

Kindly help me get answers to these questions. I'll truly appreciate any support in this regard.