Clarification on what to do if I am seeking feedback on a solution

I am currently studying a couple of disciplines on my own through reading. Have a couple of queries regarding he usage of this site..

$Q_1$: What is the site policy on posting solutions to exercises found in standard textbooks and looking for feedback on it. As in if I am unsure about certain chosen exercises is it alright if I post my solution and ask if it is correct enough?

$Q_2$: Say I have just finished completing an exercise which is actually a question that has already been answered on the site. If my solution is different to all of the answers to that particular post or if all the answers to that particular post are too sophisticated for my level should I post a new question or should I post it as an answer to the above mentioned (already answered) question which is pretty much on the same problem?

Looking for some clarification. Thanks in advance.