Constant State of Having a Crush?

Is always having crushes weird? I don't think so. Unless it takes so much of your energy that you're failing at other things like school or outside activities, there's nothing bad about it (and trust me there are people who would like to constantly feel they have crushes on others). Having romantic (or even purely physical) interests in someone can vary depending on your personality, how you perceive yourself, your health, etc (I'd find it normal for example that a depressed guy doesn't have crushes, or less crushes, than another one; I can attest with my personal experience that it's a factor). So I'd say if you're so obsessed that it's impacting your daily life then actually, yes, there's a problem. What can you do about it? I have no clue. I've never experienced such a thing, so I never sought any mean to reduce that kind of behaviour. You could try worsening your sadness/depression, or slap yourself every time you think about a guy, maybe that'd work (I'm kidding).

Is the "stalking" normal? As long as you're not invading their privacy (i.e. looking for things that aren't publicly available) or spending ridiculous amounts of time researching, honestly, I think it's normal. A bit creepy, maybe, but normal, although, it does seem like you're spending way too much time thinking about guys and researching them, according to your own words.

Now, I don't know what's the right amount, only you can judge by assessing whether or not important aspects of your life (school, activities, etc) are impacted negatively by your obsession.