complicated dependant visa questions-need your expertise!

I am seriously confused about what to do about my baby's visa. Once again, I come to the forum to seek your expertise 

Here's the problem.

Me, my spouse, and my daughter are on Tier 2 visas. These expire in July 2013. We happily had another child in August 2012. I applied for and received baby's US passport last month. I then started to search about getting baby's UK dependant visa and got very confused. I sent an email to public.enqueries@homeoffice.gsi.gov.uk but have not heard anything back even though its been 3 weeks.

Firstly, I am not sure which dependant visa form we need. He was born in the UK, and not filing at the same time as the sponsored person.
Secondly, the rest of the family's visa expire in 6 months. At which time, we plan to reapply for an additional 2 years. So, does this mean that baby's visa will also expire in July? If not, will baby have the full 3 year visa?
Also, I think I read somewhere that since baby's visa is filed separate from the rest it will cost £580 (or about that). Considering that the rest of us will have to reapply in 6 months time, this fee is rather high. It is especially high if we have to reapply for him as well.
Thirdly, we are planning a trip back to the US soon and probably won't have baby's visa sorted by then. Any chance he will be allowed back in as a visitor status until this is all worked out? And if this is possible, I wonder if we couldn't leave the country for a short trip later to get another passport stamp to sort of lengthen out baby's time here without overstaying, and then we all reapply at the same time?
Have any of you encountered this and do you have advice?
Thanks so much!

Hi I won't be much help but will be following this as we are here on Tier 2 and expecting another baby.

My only experience was with DD1 awhile ago and at that time we had to get her own visa done before she could "enter" the UK.  We did it after we flew to the US with her and made sure to have it before our flight back.  However this was when you could still get it processed via a courier and it was back within a couple days.  I'm not sure if they can enter as a visitor and everyone else on a Tier 2.

Also, if we could apply for the visa when we go back to the US, there seems to be different forms so I think we would have to apply for it here. But, I really don't know. It's so complicated with our visas expiring soon-ish. I wish we could all just reapply for visas now and include the baby. Then, we will on be on the same timescale.

Why can't you do just that - apply for your new visas now and include the baby?

I just thought that it was way too early to reapply. Do you think the home office would accept an application 6 months before they expire?
And if they did so, would that mean that my current visa will end early? Ugh, I really need to speak to someone at the homeoffice. I could call them and pay for it but I would think they couldn't give me answers to my specific case so thought it would be a waste of time and £'s.
I just know there has to be others out there in a similar situation. But no matter how hard I search on the home office website, I can't find the answers.