Firstly, is this guy just a friend or somebody who is romantically interested in you and vice versa? Because it sounds like the latter could be the case!
The blushing emoticon indicates a feeling of shyness, and a mixture of embarrassment and giddiness when feeling complimented. If he often uses blushing emoticons in conversation with you, that could be exactly how you make him feel!
Exclamation marks are generally used to assert a point, so if he often follows his statements with exclamation marks, he is probably trying to drum his message home to you. These could all be considered clear indications that he is interested in you.
On the other hand, it is also quite common to have a specific writing 'style' in online conversation. So there is also a chance that the exclamation marks, asterisks and blushing faces are all his 'thing.' If you really want to get to the bottom of it, you could always ask somebody else he talks to if he does the same with them. If it's only exclusive to you, it's pretty clear how he feels!
