Make changes in Wordpress Theme

I need to get a theme installed after some customization on the theme. Let me know quote for that. I will buy the theme myself. ##This is the theme that I like: [login to view URL] ##However, I want the header to be like this theme: [login to view URL] The header would have an option for Home, one option for categories, that will open a full blown menu for categories, icons for FB and Twitter, and in the end would be Google Search (I already have Google Search on current website). The header would be same on all the pages, including home page. The header would be sticky. Do note that we are still debating on whether we keep a single option for category, or multiple categories. Attached screenshot gives a brief idea of header. ##Below header, let's keep an option to add a 728*90 ad, center aligned. I might never use this and in that case this part would not show up. I am ok in adding code for this directly in theme file, so no changes required in admin panel. As per my understanding, the theme inherently comes with a visual builder to create home page. Only thing which I am not sure about is whether it gives option to add pagination at bottom, which I want. I will probably get in touch with theme developer for that. ##There would be changes in Post page to remove some elements and resize others. Attached screenshot gives a brief idea of top part of single post page. Apart from other elements in sidebar, we would want to show Author Bio at top. This would appear only for those writers who are currently active in the website (I am assuming there would be simple if/else based PHP code that can be added in which each author name can be specified, and going ahead I will manually edit that based on new writers who join). ##There would be some custom fields on the post page. I have a custom posts plugin installed for that. ##All the static images should be replaced by a CSS sprite. ##Suggestions from Google page speed should be implemented for performance. ##For Google ads, need to ad code using if/else, so that different ad codes are displayed based on screen size. ##All the changes need to be done in such a manner that it is easy to upgrade to the next version of theme in future. Possibly setup a child theme (I believe the theme supports it). ##And most importantly; the theme is full responsive right now, and it should stay like that.