Question regarding multiple BHO instances and toolbar button

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IE7

C#

Windows

.NET

IE

I want create BHO and toolbar button. My BHO must collect data from page when user submit form (only in case when user logged in). From toolbar menu i can login/logout and change some settings for my BHO. I have several question regarding this task :
1) How i can get settings for my BHO from toolbar extension and change toolbar from BHO?
2) Is this a good strategy to put my toolbar code in BHO assembly. But there another problem. Browser create new BHO instance for every tabs, is this mean toolbar will be created every time with new BHO instance?
3) How i can use only one BHO instance for all tabs or share some data between all BHO instances for example information about logged in user.