I have solved my problems, the mylyn plugin is up and visible in redmine so now I can connect redmine with eclipse.
Followed this steps:
1. cd [redmine-install-dir]/plugins
2. git clone git://github.com/danmunn/redmine_mylyn_connector.git
3. cd ..
4. rake db:migrate_plugins RAILS_ENV=production note for this for newer redmine versions run rake redmine:plugins:migrate RAILS_ENV=production
5. bundle install --without development test
Also note that the plugin requires libxml-ruby.gem, simply run in cmd this
gem install libxml-ruby
This in case if error comes up, maybe you already have libxml.
I also have win7 64bit, redmine stack 2.6.0-1
Best regards, thank you all for useful comments.