I can answer all that with one recommendation.  Get yourself a .com domain name (host not needed), direct your domain name to your blogspot blog.
Blogger will still host for you, your previous posts will be there and you can get yourself you own domain name. How nice...

Just go to Setting and choose Publishing. You'll see a custom domain there. There will be the place to go after you have your own domain.

as far as i know, there's no problem adding ads or other script in blogspot. but only in template

If you are using blogger beta, even easier, just click template > Configure script / HTML and paste your ads code.

There's also an option to edit HTML under the template tabs

i just registered my own domain name with eternal solutions.

but how do i link it with blogger?

what is the name server for blogger? i tried ghs.google.com but invalid name server.