Yes it's alright for men to wear short sleeve shirts.Like you said the more conservative,the better and that rule applies to men as well.As this is a conservative muslim country,total respect for local customs and traditions need to be observed.Women aren't advised to wear sleeve less shirts or tops as well as shorts.Business dress code is the same as anywhere else.For men formal suiting and for women nothing specific bit it has be decent so as not to offend anyone and more importantaly,to avoid any sort of unwanted attention.