DETECTION - Do I need to create a mobile version of the website?

Hi Community

I've been building a few websites here and their as a part time freelancer. I am starting to do this more and more as a full time job.

I have a very novice question and please forgive if i am posting this in the wrong area.

1. Do I need to design a mobile version of the website I create? or I should say mobile versions of the site.

2. Should this be handled as standard practice or do I need to charge my clients more? I mean should I handle it as an option and openly acknowledge that I have to design for mobile phones?

I test for IPhone, IPad and Android but that can hardly be categorized as designing a site for a mobile phone since these phones have the ability to display websites almost the same way as a regular site.

Which actually leads me to a third question.

3. Should I design a separate web site for an IPhone, IPad or Android.

Thanks in advance for your advice.

you can develop separate site for mobile device by using mobile detection code