First 6W Ultrasound...what to expect?

Tomorrow....the biggest day so far in my pregnancy....the first ultrasound!!!! I've done some research but wanted to get some feedback as to what to expect and what to ask? I know that I should be looking at the size (2-5mm or 0.08-0.16 in) and heartbeat (100-140 bpm). Is this correct? Anything else? Also, I have a probability to be preg with more than one...anything else I should ask?

[usuk]

I am not sure you will def see HB at 6 weeks. You should see the embryo sack and maybe the fetal pole starting. Also the nutrient sack. By 5 weeks they usually can only guarantee that it is not ectopic. But HB could be at 7 weeks not always 6 weeks. Good luck :)

[MicroIsabella]

I went for the U/S and got the best news ever.....Twins! They both measure 4mm but could not tell me about their heartbeat, althougt we saw their hearts beating fast! I'm so happy! Thank you al for your comments!

[yang_k23]

OMGahhh!! Double congrats girl!!! I'm so happy for you! Did you do iui/ivf?? I did relations/follistim/ovidrel and the day we triggered, i had 3 mature follies so RE did stress to us that we are at risk for multiples which we were ok with.