First of all I llive in a mobile home/trailer. Lately I have noticed that the toilet bowl is leaking a little water. I can't find a leak but when you sit on the toilet you can hear a drip. Also you can sort of smell sewage sometimes. I have tightened the flange bolts, but still have this problem. My questions are:

1) Is this most likely a flange problem?
2) Will mobile homes also have cast iron flanges?
3) How would I know what type of flange to get?