What is the difference between company name, brand and trademark?

I have some ideas that I plans to execute later. But for the moment, I want to "secure" the name, logo etc. of the business. I for one cannot seem to figure out the difference between the company name, brand, trademark and such concepts. After having read some things on the web, I know (or at least I think I know) the following:

1. Registering a company name is not a great option since it lapses after 60 days in case the company is not incorporated (in India).

2. Any other person who gets a trademark registered of the same name as point 1 can legally sue you for use of the name.

3. The company name has enough protections built into it to make sure that variations of the same name are not allowed.

The following, in brief, are my questions:

1. If I get a trademark registered, does that mean I do not have to register the company name etc., considering validity (time period) of the company name?

2. If I have a trademark, is that for the name of the product, the company name or the logo?

3. Do I need to register a separate trademark for each variation of the logo?

4. If the trademark is of paramount importance as far as "protecting" the name goes, then why bother with company names at all?

5. Also, if I am working for a company, then does any other company name/trademark etc. that I register also belong to the company I work for?

P.S: Please feel free to add more questions that I may have missed. This is all I could come up with at the moment.

P.P.S: Since I am in India, it would be great if answers could be India-specific, or if the answer could be specified with a country-name at the beginning (in case you want to answer for a diff. country). But I would assume that the basic concepts of trademark, company name etc. would not really differ from country to country.

In the USA:

1. If you register a trademark, you don't necessarily have to register the company name, although it is normally done. A product or service name is likely to be different from the company name.
2. A trademark can be for the name of a product, a company name, a logo, or some combination of these.
3. A trademark protects you from other people using marks (names, logos, etc.) that are confusingly similar to yours. If the variations of your logo are almost identical, it may not be necessary to register a trademark initially. But it might also be safer. You might be able to include variations in a single trademark application; I'm not sure.
4. An separate company name is useful if there is more than one product or if the company is more important than the individual product. eBay is a good name for eBay, because the web site is the primary product of the company. However, since Ford makes a lot of cars, the company's name itself has recognition value.
5. Some companies claim ownership of all intellectual property produced by their employees in employment agreements, whether at work or at home. This may include trademarks, copyrights, and patents. You can check the employment agreement for details. I believe the law in this area has gone both ways in some court cases for situations without employment agreements.