We are in the process of developing a software that provides service to internet users and we would like to ask about the legal liabilities of some issues. Of course, everything is to be done with the consent of the user of our software but our concern is about third party tools and services that may be invoked/used by our product. In particular, these are the concerns:

(1) Embedding a toolbar to an existing browser. This screenshot is an example, where the words in the highlighted toolbar are passed to www.google.com for searching, and the contents of the window are the results of the search. I want to know if any consent should be obtained before such a toolbar can be embedded in a web browser, whether there are any legal requirements by the web browser; whether different web browsers have different requirements (at least for Internet Explorer, Firefox, Chrome, Opera and Safari).

(2) Invoking a free website from that toolbar (like Google’s search page). The screenshot above demonstrates such an existing toolbar.

(3) Full ownership and unrestricted access to the data entered to this toolbar. In the screenshot above, I want to take the words (translation english to spanish) and own them, i.e. storing them in my database and do some processing on them.

(4) Ability to track the pages entered by the user starting from that free website. In the screenshot above, you can notice that the user opted only for the third result, whose URL is translate.google.com. I want to have access to this and all URLs clicked from this page for some processing as well.

This is a commercial application, so I need a very concrete, precise and reference-supported answer.