I think this is a good style for your sister.  It looks great on her. 

Going to the fabric store without knowing how much I need for a project.  If I can't find the exact pattern then I guesstimate how much I need and usually end up with an extra yard or more. 

I think it will depend mainly on what type of sewing you want to do.  The Sewist has more presser feet.  The presser foot tension is adjustable but paying more depends on what kinds of fabric you plan on working with.  There is also a needle threader but in my experience 95% of the problems I have is getting the needle in the right spot to thread and without an automatic up/down option this feature may be useless.  If you plan on taking classes the hard case will come in handy to protect the machine or there is the option of the sewing machine trolley at JoAnn's (about $45 with 40% off coupon). 

Without having a model number or a picture of the machine it's tough to say. 

If the straight stitch is it's own setting (zig zag is a separate setting) sometimes adjusting the stitch width may move the needle back.  If the straight stitch and zig zag stitches are the same setting, just width differences I would try contacting the manufacturer.

You're waiting until tomorrow to start?  If I had that kind of excitement there's nothing that would stop me. <teasing>  Congrats on your new machine and have fun with it.

Make a packet of the Lipton Alfredo pasta & sauce.  Cheap and easy shrimp alfredo.

Have you tried making a duct tape dress form?  Even with the store bought ones they will not be an exact duplicate of your shape and it will need adjustments once delivered.  

If you haven't tried to make a dress form it might be worth it to try first. Here's some Craftster's posts on making the dress form:
http://www.craftster.org/forum/index.php?topic=346512.0
http://www.craftster.org/forum/index.php?topic=341386.0

I'm not sure what tape options are available in Trinidad.  You will want something heavy duty.  The duct tape we have in the states have little strings in between the tape layers running both vertically and horizontally.

I was able to find an owner's manual online for one of the Rowentas.  Come to find out the leaks may be due to the kind of water used.  What I grew up learning is to use distilled  water (although I never did) while they say specifically not to use distilled. 

After seeing the owner's manual I went and bought the Rowenta Focus.  The only possible downside I see is it has an automatic shut-off and with sewing I spend time waiting for it to reheat.  I don't see how I can avoid this unless I were to buy a steam machine.  Thankfully it doesn't take long to heat.

Here's a strata recipe with canadian (back) bacon and english muffins.  It's very yummy!  I would guess as long as the egg and milk amounts stay the same anything can be tossed in.  

http://www.pbs.org/everydayfood/recipes/Canadian-Bacon_Strata.html
From the show Everyday Food on PBS.

With the machine eating thread it might just be a tweak in the needle size versus the thread used.  What I've been told is pick the needle based on the thread used and pick the thread based on your fabric.  In essence all three need to be in sync with each other. 

Also stick with better brands (i.e. Coats & Clark, Sulky, Gutterman) and stay away from the bargin bins as in the long run they're not much of a bargain.  The cheap ones are more likely to break, pill, fuzz and give weird problems.

My machine doesn't like Coats & Clark with a size 14 needle (tension issues) but has no problem with Gutterman.  I prefer the latter anyway so that's what I'm sticking with.