[sarah]

I am far from a knowledgeable person on this subject however you are right to be vigilant and concerned even at your early stage. getting chemo is good but I think you should also ask about radiation and see a radiologist, maybe get a second opionion from another oncologist and ask about drugs such as raloxefene and tamoxifen.
don't take supplements while doing chemo but do check out for later curcumin/tumeric, fish oil and others (see other posts) and also co-enzyme Q10 for the Herceptin and heart issue but check all of this out to be sure it fits you or not.
I started off (and I'm sure I'm not the only one on this site) with DCIS, no node involvement and now suddenly I've got invasive cancer so make sure the doctors do the most possible. Good luck, you're at a very early, treatable stage. they say as long as the cancer is in the breast, you can't die of it. it's when it excapes that it gets interesting.
I will try to answer your questions:
1. longevity - should be excellent
2. the chemo depends on different issues. Also if one doesn't work, they'll try another.
3. Herceptin is excellent for HER2+. It works best with certain chemo, and can have heart problems with others, but your doctor should know this. Herceptin I think is now being allowed for stage 1 and if it is, I think most of us would say, ask for it but maybe someone with more knowledge will answer. Definitely speak to you oncologist about Herceptin and if he says no - really push to understand why not. I had Taxol with Herceptin - I think there's some synergy between the Taxanes (Taxol and Taxotere) and Herceptin but as I said, I'm not an expert.
Remember at your stage, the cancer is very treatable.
stay positive, fight hard
sarah