abhishekjoshi84 on "A dropdown list of specific links(posts or pages)"

Hi, I am fairly new to this and appreciate any help from experienced bloggers.
I have created a blog(linked to my name) and have several categories. I wanted to add a dropdown list for some specific posts or pages either on a separate page/post or on the sidebar. Have not been able to find a way to do that. Went through various threads on the forum but could not find anything which might help even though there are somewhat similar questions on the forum but they are quite old and their it is mentioned that it is not possible.
To be more specific here is what I want to do:
I have several categories and a dropdown for categories in the sidebar as well as categories listed as menus in the header. What I want is a dropdown for all posts of a specific categories(Movies->Revies-> links to all posts for reviews) anywhere on the blog. Is there a way to do so?
I tried putting HTML code for a simple dropdown on a post but when I save it the dropdown goes away.
Another question is up to what extent HTML is supports on the posts(In new post the HTML edit option instead of Visual)? Is it not possible to add custom HTML content there(No CSS or JavaScript, only pure HTML)?