We Have a site which includes asp.net and classic asp also,
But Now we want to migrate our site fully into asp.net
in terms of only url changing, we are not going to change domain name,
we want to change only page urls i.e. from .asp to .aspx
www.abc.com/pqr.asp to www.abc.com/pqr.aspx

Question 1 : If we use 301 Permanent Redirect, is 301 redirect itself sufficient way for page url changing?
will it affect our ranking in seo which we achieved over a years.

Question 2 : Is there a need to contact webmaster of every search engine/directory sites for
updating request of changing urls where our site is listed?

Question 3 : What if we are using above methods then how much time it wil take to get indexed .aspx pages in
search engines like google,yahoo,bing etc.. and
Please suggest whether any issues occurred by adapting these methods

Note : We are only using free submissions to submit our site pages to different directories.
(No Paid submissions we have yet used.)

Is there any other fastest way to migrate from .asp(asp) to .aspx(asp.net)
without affecting our seo page index ranking?