Yes, to enter Thailand you need a valid passport with minimum remaining validity of at least 6 months.

Currently, no need to get visa. You can directly go to Immigration at Bangkok airport.

Yes, Thailand is a destination for the whole family

High season and Good season is November to March. Hotels will be expensive during this time and it is crowded. Off season is April to October. April to July is Hot season, August to October is rainy

Yes, absolutely safe. Every year 1000's of Indian women visit Thailand

The best option is Indian restaurants. There are many Indian restaurants through out Thailand.

No, Thailand is a tourist destination for the whole family

Bangkok, Pattaya, Phuket, Krabi these are very commonly know tourist destinations.

You can book hotels in travel portals like Agoda.com, Booking.com, etc.. you can check reviews for the hotel

I have listed some suggested tours. Please scroll down to see the packages.

It is individual opinion whether to go with agency or make own arrangements. I would suggest to go with tour agency when you travel with your family. It might be hard for you find all the things at ease.

It depends on the package you purchase. There are packages available including Indian food.

I would say, it is highly impossible to get Telugu speaking guide. There will be a Thai guide who speaks English/Hindi (very rare)