There are no restrictions to your travels when on Spouse VISA, you can basically travel as much as you like and come back to the UK before the VISA expires. However the time spent outside the UK is looked in and the settlement application is considered on many other variables including the time spent outside.
Currently there is no limit in terms of time spent outside the UK and number of visits/tours done on a spouse VISA be it pre or post July 9 2012 changes.
Applying for British Citizenship does have a requirements on the maximum allowed time out of UK.
You can check the details on UKBA website:
http://www.ukba.homeoffice.gov.uk/visas ... ettlement/
Hope this helps.
PS - Personally I would not spend more then 3 months in a given year without any good reason.