Preparing for my first baby shoot

Thanks for all your advice. This is relatively unknown territory for me, but fortunately it's not action photography and I'll have time to think things through as I go along. I'm preparing myself by shooting dolls at home and looking up poses for ideas and inspiration.

My Sigma 17-70 only stays at f/2.8 around 17mm and quickly stops down beyond that (35 and 55mm settings are at f/4) and the DOF calculator shows quite a difference between f/1.4 and f/4 with a 50mm setting, so a Sigma 50 f/1.4 should make some difference in that department. Besides the shallow DOF and overall faster lens, I've never found my 17-70 satisfactory in the IQ area, and I do want sharp quality shots and I'm willing to invest in a new lens (in this price category at least) if I will get better results and for future jobs. I don't feel I'm getting that very sudden shallow DOF unless I get extremely close to the subject, even with my 35 f/2. Perhaps as stated earlier in this thread the shots I've found online have had some serious blurring done to them in post processing. The 70-200 f/4L doesn't seem suitable for the job at all as I get way too close and besides, without image stabilization when used with a 1.6x crop sensor I experience some serious shaking when not using it with a tripod.

I do hower agree with your point about out-of-focus shots being a bigger problem than having to "fake" the blur in Photoshop although I've heard many warn against doing it because it makes the photo look fake. If money was no object I would probably look into tilt-shift lenses for this sort of thing.

Lighting: yes, the Elinchrom stays at home. I'll have enough gear to bring along as it is. I'll have the 580EX II, 430EX and a stand with a small Elinchrom white shoot-through umbrella (83cm/2.7 ft.). I figure that if I use a PC-sync cable for the 580EX II, I can trigger it off-camera and also have the 430EX off-camera, triggered optically with the aid of a hotshoe optical trigger (both in manual mode of course). As I only have one stand/umbrella adapter I'll need to place the other flash on the stand that came with the flash. I'm not sure how I should position the lights yet, but I'm thinking the umbrella should be at the usual 45 degree angle to the left or right of the baby and a little bit above (though 45 degrees high seems too much if space is tight in the room and I have to bring it close). The other flash I assume would be good for lighting up the background, possibly reflecting off the roof/walls if they're white. I also have a large round 5-in-1 reflector and a silver-reflective Elinchrom umbrella (also 83cm/2.7ft) but I believe the latter will give a much harder light than with the white shoot-through.

Tending to get "muddy" shots I believe that's mostly due to not having used much flash up to now, so with proper lighting I assume that would make post procesing in Lightroom and/or Photoshop much easier and give me better possibilities (despite not having a FF camera)