In US on H1B, want to get employment based green card.

[jitensyaotaku]

Here's some history to begin with:

From UK
Have been in US on:
J1 18months
B1/B2 5 months
Have never been out of status, always filed taxes, no criminal record.
H1B (Just starting 4th year)
Have a BSc Hons 4yr degree.
Have 3+ years post-grad work experience with the same employer than I worked with some 9 months of my time on J1.
H1B due to expire in July 2009.

Have my H1B extension but need to leave the US to get the passport stamped (if I plan to re-enter the US). Do I need to get this done before submitting a GC application?

Just got a H1B extension in July this year... Can I re-use the I-140 petition from that time seen as the GC would be for the same job with the same employer?

My questions are:
1) Is it hard to get H1B -> Green card through HB3 approved? An immigration attorney told me before that I have a snowballs chance in hell of getting it approved... Basically said that if one person applies for my job then the GC application gets rejected?

2) I presume there's a lengthy wait for H3B green card? If the wait is beyond the expiration date of my H1B, can I remain in the US working or would I have to leave the country?

3) Any ideas of what costs are involved?

I would presume that already being here on H1B .. I'm already a speciality worker etc... so is it really that much harder to get a GC based on my employment?

Thanks for any replies...