How many upvotes are to many?
The details of the script are not public, to avoid users working around it.
If I write a comment to every answer upvoted about why I think it good, would the system not reverse my votes then?
For reasons given above few (not even including per site mods) know what the system does exactly, and those that do know are not supposed to tell you. Certainly the time between votes and/or potential other actions between votes in some way do play some role; whether the threshold are chosen so that one comment in between will change anything, I don't know.
It might help you though when somebody should start to inspect your account specifically for voting irregularities. (Then, accompanying each vote with a comment is not desirable either.) And, even with comments, you should be aware that you are entering a gray-area with your actions. Following and disproportionally voting for or against a particular user's account will raise red-flags. One is not really supposed to do this, even if there are no ulterior motives.
Added: In a way it is the same as in Are my serial downvotes inappropriate? Just in the other direction, though not every argument applies vice versa.
Let me further add that while I can understand where some are coming from and I do not propose to be overly rigid regarding this, beyond all technicalities I simply feel that it is undesirable if a lot of such voting happens.
The point is that I believe that it unbalances the system a bit in favor of those that already have many posts and points and are around since a long time. Even when they are in this position based on their merits and contributions, this does not mean that it is a good idea to introduce aspects into the system that gives them an additional edge, and might indirectly discourage or frustrate others.
Moreover, if 'following' users is alright, then it can happen that the system is unbalanced based on pure happenstances. Some users happen to know some other users that are also on the site and they follow each other as they have similar interest and find each others contributions interesting. They actually read and find their respective posts good and thus vote in perfectly good faith. Maybe not even on each and every of the others posts maybe just 1 in 3. For a group with a several members, this will give any involved account a considerable boost. I think it is better to avoid such unbalances.