to answer ur first question..any car with automatic fan and a thermostat valve would take temperature to middle within a few minutes...they are designed this way so that car's system could perform at best..as mentioned by a brother earlier there is a certain temperature where a car is performing at its best...so thats perfectly normal u dont need to worry about that...u may have noticed ur heater would not work that efficiently when ur car is cold but as soon as the temp guage hits middle...heater starts performing at its best..this is wat thermostat valves and automatic fans are for...
n yes my brother...alto is a petrol guzzler...u r not the only victim of this problem ... having a carby engine..it sucks petrol like anything.... very very bad average on petrol....
n about cabin noises..that too being a pak suzuki made car...is a gift for u so enjoy it .....or like me..install a sound system n play it loud so u dont get to hear those cabin noises anymore ......
hope i answered all ur queries well enough....
wrote a pretty long essay ....