Hi and welcome to the forum!
Its okay to not approach men, that’s the guy’s job. If you tend to by shy and feminine, definitely go with Instant Sexiness B. IS/b will enhance your femininity in a positive way, and give you more of a soft, sexy kittenish aura. Think Marilyn Monroe. To help you feel less shy and awkward, definitely go with Instant Openness. IO will relax you and those around you, everyone will be friendlier and conversation will flow much more easily.
In answer to your questions, yes, they really do work. You do need to test each one separately at various doses (or number of sprays) until you find your “sweet spot” or the amount that produces the most effective results. This should help How To Find Your Sweet Spot (How to find your sweet spot...) .
The only negatives are if you use too much, you can cause a “ghost effect”, where people will actually ignore or avoid you. This is why its important to find your sweet spots for each product when you first get them. Also, you should take two days off from phero use each week, to keep your neurotransmitters healthy, otherwise you can start to feel kind of burned out (I learned this the hard way).
For the gift certificate, this post should help How do I qualify for a $25 gift certificate?