Had my 07 plate Signum for 2 weeks now, 1.9 Diesel 150 Design. I'm having a few problems which I need help on

1 When cold there is a judder feel coming through the steering between 65-75mph, nothing major. Before I bought it it had a judder at 60mph, bad and the tracking was 2degrees out. When I re tested it the judder then happened at 70mph, nothing major, checked it again and they said that the tyres were slightly feathered so they swapped them out for another set from another car, which seemed to cure the problem although only until now, some times it pulls to the left too but not major.

2 The auto headlight sensor seems to keep the lights on longer than I would expect until the car hits strong sunlight, then they go off.

3 Used the car last night parked it up locked it, went to sleep. Went out this morning in the wifes Zafira, came back at about 11am. My boy was outside until about 2pm when it started to snow, he came in and about 4pm, there was a knock on the door and the neighbour told me that the windows were open and the alarm was going off. Snow all over the interior, and the doors locked!!!!! The keys had been hanging up since the night before and had been nowhere near the car, so I got Henry out and hoovered up the snow.

Does anyone have any idea before I phone the dealer in the morning, up to now they have been very helpful. The car is Network Q and done about 800 miles since I picked it up.

Need any ideas

Thanks in advance