Welcome to the STD forum. I'll try to help.
Even though genital HPV is sexually transmitted, it doesn't behave like most other STDs. Almost everybody gets it and catching genital HPV is a normal and expected consequence of human sexuality. You were a little less lucky than some people, because you developed overt warts and an abnomral pap smear. You need to follow your provider's recommendations about follow-up and possible treatment of your abnormal pap; if you do so, you will be completely protected against a bad outcome (i.e., cancer). If you and he have been having unprotected sex, you can assume you and he are now sharing any HPV strains that either of you had. This has no serious implications for your partner's health, except that he needs to keep an eye out for penile warts. To the specific questions:
1) HPV just about always clears up eventually. usually in 6-24 months. Persistent pap smear abnormalities after a year are not unusual. As long as the pap smear shows only low grade changes, the usual recommedation is exactly what your doctor has told you: repeat pap smears every few months to keep an eye on it, expecting that eventually it will clear up.
2,3) Oral sex is safe. The genital HPV strains don't usually take hold in the mouth or throat. When they go, usually there are no symptoms and they clear up. Actual warts are extremely rare. As I said above, you can assume your partner is already infected and that no harm will come from it. There are no restrictions on your sexual practices with your partner.
4) You should tell him. LIkely he'll find out somewhere along the line. You can reassure him about his health just as I have. (Show him this reply.)
5) There are no data for the transmission risk on a per-encounter basis. But it's probably pretty high, at least a few percent.
6) My guess is that you have only one infection. The low risk (wart-causing) HPV strains often cause cervical infection with the sort of low-grade pap smear changes you have. However, there is no way to be sure and it really doesn't matter; the recommendations for both you and your partner would be no different regardless of HPV type. In other words, I agree with your gynecologist that there is no need to test for HPV at this point.
One more thing: Tell your doctor you want to be immunized with Gardasil, the HPV vaccine. It will protect you from some of the most likely additional HPV infections that you might otherwise catch in the future.
Please use the search link for many, many discussions about all these issues. Here are some you can start with:
http://www.medhelp.org/posts/STDs/HPV-Transmission/show/761416
http://www.medhelp.org/posts/STDs/Confused-about-hpv-interpretation/show/763984
http://www.medhelp.org/posts/STDs/hpv-and-oral-cancer/show/758844
In addition, there are some excellent online sources other than MedHelp. See CDC (www.cdc.gov/std), the American Social Health Association (www.ashastd.org), and the Westover Heights Clinic of Portland, OR (www.westoverheights.com). (Full disclosure: Dr. Hook and I are on ASHA's board of directors and WHC is owned and operated by Terri Warren, who moderates MedHelp's herpes forum.)
Bottom line: You should look at your HPV infection as an inconvenience, nothing more. It will not become an important health risk for either you or your partner, as long as you follow your doctor's advice about follow-up.
I hope this helps. Best wishes-- HHH, MD