I have a 18 by 25 foot metal building I want electric service to. I will have a welding machine that will need a 220 plug in. a air compressor that may be a 110 plug, besides that it will be general shop tools such as grinders, drills, computer, office equipment as well as power tools used in the 110 plugs. I will also put a small freezer and small icebox. I suppose I will have around 4 or 5 breakers of the 110 and 2 of the 220. It will be just a home shop for small repair and projects.
Do I need to go to a 200 amp or will 100 amp be enough?

The cost difference between a 100 amp and 200 amp service is low enough that I would recommend that you install a 200 amp service. This will insure you have enough capacity for future expansion, and add to the resale value later.