1. If surprise is an emotion, Adam would not have it.
2. If surprise is not an emotion, Adam could have it. I would probably define it as a volition to assent to the proposition that all things will work together for good for the elect (Rom. 8:28).
I am undecided. Have to think about it more.
By all means, take your time. But as I said, you will, at some point, have to provide an original argument for your original claim. I see no Scriptural nor experiential reason to think that emotions are only possible in response to negative events and only cause the mind to think irrationally.
To that end, I just would like to point out that your #1 is, at present, an assertion without argument. As it stands, it begs the question by presupposing your unargued claim that emotions are only a postlapsarian experience. It should be the other way around: you should be presenting an argument for your claim that emotions can only be a postlapsarian experience as well as explaining how my hypotheticals are either impossible or compatible with your claim.
With regard to #2, that definition does not strike me as fitting with the Scriptural usage of the term. For example, one can be surprised and respond in a negative way. The wicked are often "surprised when you do not join them in the same flood of debauchery, and they malign you" (1 Peter 4:4). Further, volitional assent to the proposition you mention does not seem to be a good example of surprise. We can expect God works all things together for our good is something. Surprise, I think, is caused by something unexpected.
I see no reason why angels cannot be surprised in this sense, by the way. I can imagine that the
protoevangelium to Adam and Eve in Genesis 3 may have come as an unexpected surprise, for the good news contains revelation of which angels are said to "long to look" (1 Peter 1:12). Again, if this is even
possible, then the definition of emotions you provide would not be sufficient.