You know you're in love when you don't want to kick them out of bed the second you're done having sex.

None of those. Think about how you are with your best friend. Now make that feeling better. That's love.

All of these would probably be a sign...but I'll go with #1.

The first four could determine lust but I think number five is the best, because it really means your committed.

Well, I don't know why we have to choose just 1. To me, it seems like love would include the whole group, or at least the first four. That fifth one is more variable because some percentage of the population is polyamorous. They frequently choose one primary partner, but may enjoy having sexual encounters or small-scale relationships while they are still with the primary. This does not mean that they cannot love the primary (or other partners), it just means that exclusivity is not something they need to feel in love.

As far as the others:

1. By itself, I'm not sure if this a sign of love or simply finding their appearance really compelling, magnetic. I can think of several women that I know that are very attractive, but are not people I am romantically inclined towards. It can be hard to take my eyes off of them, but I know I'm not in love with them. On the other hand, if you find yourself constantly staring at someone who you are not naturally attracted to physically, that may be a sign of love. But probably not by itself.

2. This is probably the one I would pick if I absolutely had to pick one (with #4 being my second choice.) I can think of a lot of woman that I've been romantically interested in, but only a handful of them seemed to actually alter my mood (at least positively) when I am around them.

3. Again, I think this one is more variable. I know some people who are just very touchy-feely people. I've had more than a few women frequently touch me (and anyone else around them), but I know for a fact that several of them were certainly not in love with me. I myself tend to be very hands off until I am in relationship. When I am dating someone, I will make much more physical contact with them, whether I love them or just like them.

4. Although I am somewhat skeptical of that 85% statistic, I can think of several women who seemed to be on my mind throughout the day, and I'd say I eventually fell in love with all of them.

So, I'd rather consider the list as a whole, and make modifications based on people's personal differences. But if I had to choose one, I'd go with #2.

I'd have to go with 4. I agree that 1 can be creepy if done too much, and 3 precludes "crushes".

I would say number 4 when I am in love I can't stop thinking about the girl.

None of them. Love cannot be explained; noone knows what it is. I can't be without my girlfriend - she is my everything. That is about as close to an explanation as I can give.