Everyone will tell you what should be your best beginner gun, but, the truth is that the previous post is the most accurate. You will need to define what is the best gun for yourself. Also be open minded enough to realize that once you make up your mind, you can change it as well. Carrying around a full sized auto in all situations will get very old, very quickly, especially since there are some very good options (both ballistically and ergonomically) in compact and sub-compact handguns (both revolver and automatic).
If you are able to, go to a range and fire as many guns as you can while still being able to be objective about them. You will naturally move towards what you can control and use the best. Also realize that to truly carry every day, one single handgun may not fit the bill. You may need two or three (full size, compact and sub-compact / pocket gun).
As for your carry protocol, the same is true. Most will tell you that an IWB Kydex combo is best. I don't know of anyone who carries on a regular basis that doesn't have a drawer full of holsters. Why? Because you may need a different holster for the same gun for different carry situations as well as trial and error. You may love one today and find something better tomorrow.
Truth be told, just like everything in life, it will take time, trial and experience to figure out what is right for YOU. If you are not part of an agency that dictates what, when and where you carry, the options are endless. Whatever fits you best, and you feel most comfortable with will be the best for you. If you aren't comfortable and confident, you will stop carrying and defeat the purpose of having a handgun for self protection.
Good luck, and don't forget to enjoy the process. It really can be a lot of fun training, choosing and evaluating if you look at it that way!