To answer your question point-by-point-

1. A two bedroom accommodation can legally accommodate 4 bachelors. But most of such bachelor acco's see between 4 and 8 people sharing the apartment. Please note a 2 bedroom apt normally means - 2 bedrooms, 1 and 1/2 baths, a hall , dining and kitchen.
2. This question is one of the most discussed topics in Qatar. Anyway, for a 2 BR flat unfurnished , the range is between QAR 4500 to 8000/- per month. Add 30% for furnished and add 50% for 3 BR.
3. You will find hotel apartments that allow short term and long term (min 1 year)stays. The actual agreement is a 3 page arabic document that prohibits a lot of things. Just dont bother about it now.
4. Conveyance is another hassle. Better make arrangements with a driver to pick and drop regularly. Doing this will cost between 500 to 100 QAR per month.

Now, since you are a SAP Consultant, you will understand that with the Requirements Specs provided by you, this is best feedback you can get. If your specs were more elaborate (which company, approx location of work, deal with company or sub-contractor, how many of you etc) you would have got better suggestions.

Have fun and welcome to Qatar