AB77

I recently bought a 300C after wanting one for a few years. It's a silver 2007 model, with 110k on the clock. Most of my friends think I am crazy but I think the car is FAB! I have a few questions I hope someone can help me with please: 1) What does the 'Tire bar' message mean on the centre of the display panel? 2) The battery seems a little hesitant when starting. Europarts suggest a Bosch S3 battery for around £115. Any thoughts on suitability/cost? 3) The car could do with an oil change. Is this a straightforward DIY task like most other cars? 4) The remote lock button button doesn't always seem to work. 5) The alarm went off while I was about to fill the car with fuel, not sure why 6) The front passenger electric seat adjuster for forward and back movement does not move the seat although you can hear a noise when the button is pushed/pulled. 7) Any thoughts tyres? I need 2 for the front and was a little surprised at the cost. Many thanks