A: Yes, please try the rainbow stars mailing list which has a broad base of queer subscribers, or the astrolesbians list which is exclusively for stargayzing lesbian womyn.
A: No. Each of a pair of twins (one gay, one straight) could be born near the same time with virtually the same astrology chart, so there's no way of telling...
A: For people who enjoy studying astrology.
A: Sorry, I'm too busy just now to help you (but I hope to offer my consultancy services again soon). For now I recommend you see my directory of gLbt astrologers to find a consultant who's available.
A: Free astrology charts can be made at Astrodienst. To begin making your chart go to the Direct Atlas Query and add your place of birth, then follow the instructions. When calculating your chart you can choose from various horoscope styles (via the "extended chart selection" section). You can select from several house systems (Equal, Placidus, Koch, etc) and even add "cometoid" Chiron (the comet-like planetoid that post-modern astrologers use as the ruler of Virgo), the four larger Asteroid Goddesses (Ceres, Pallas, Juno & Vesta), another phenomenal 29 000 asteroids, and even Varuna (a new asteroid out near Pluto) to your chart. You can also progress the planets, see their transits and make composite charts (for any two people). All this, as well as free basic chart readings!!
While access to the internet is required to utilise the excellent free services from AstroDienst, Astrowin provides free chart-making programs that can be downloaded and used on your computer anytime.
Kairon is a freeware program for Macs.
After making your chart you can check out readings of your Sun/Moon sign combinations at MetaMaze.
Astrologix provides a chart-making service in German. Astrolabe has a Chart of the Moment where you can check current planetary positions, and offers a free chart & mini-reading by email.
Maitreya's Dream is a free program for Vedic and western astrology.