Just thought this may be useful information and I apologise if it is well known but I went to Qatar at the weekend to visit a friend and in my ignorance thought it would be as easy as going to Dubai - it is not! Am on a British Passport but it still wasnt easy to get in.
When you arrive in Qatar, you need a visa. You will be asked what you are doing in Qatar and you must have an address to prove where you will be staying - I was only going for the day but they still wanted an address!
You will be asked to do an eye scan.
The visa costs 100QR each (10bd) and the only way you can pay is by credit card - they do not take cash (scary moment as my NatWest credit card does not work in Bahrain - thankfully it worked in Qatar).
Hope this may be of use to someone.