Start doing stretches, like reaching for your toes. Also pushups and situps will help you to tone up and improve upper body/core strength, which in turn will help you to burn more calories.
I use a serfas Acuna saddle on both of my road bikes, but if I had to try a different one I would give the Arione a shot. 'It must be popular for a reason' is my thinking.
The trek 1000 seems like an excellent bike, most big time bike manufacturers do make entry level bikes, usually a version of their mid-priced bikes with cheaper componentry. Take a look at Jamis's Ventura, or specialized's Allez, also good bikes around $700.