That looks to be the same fabric which I found in black a couple of years ago - (in the shop in Warrington which changed hands between our last two visits) and yes it was cheap.

I made a skirt which goes in the washing machine on a synthetics cycle without any problem.  If it hangs to dry it doesn't need much ironing (on wrong side) and I am pleased to tell you that the sewn on swirly bits are all still intact. 

Yes, Hobbs is probably the top brand.  They have lots of different types.

If you want to sew with stretch fabric these days an overlocker is a must-have.  It's a doddle to wizz up the seams of leggings or a tee shirt.  Overlocking is also the neatest way (Hong Kong binding excepted) of neatening the seam allowances on non-stretch fabric.

BUT - an overlocker won't do everything, you still need a regular lock stitch machine for some jobs (inserting a zip, making buttonholes, and a lot of fiddly little repair jobs).

A cover stitcher for hems on stretch fabric is a luxury; a twin needle in a regular machine will do almost as well.  Th front looks just the same but the back is slightly different.

As others have said, consider getting a second hand/vintage regular machine.  The older non-electronic machines do usually stitch very well, although if it's your only lock-stitch machine you will probably want one with a swing needle/zig-zag.  The old black Singers only do straight stitch.

You are doing your homework, which is good, but if possible you should buy a new machine from a bricks and mortar shop where you can test drive it.  My overlocker is a Bernina 115o.  When I did the test drives it was so much smoother and quieter than the Brother overlocker.  I know a lot of people on here love their Brothers, but it wasn't for me.

The roadshows I've been to were mostly patchwork fabrics, but they are organised by a P&Q group.  They do have quite a lot of batiks, and other cottons suitable for summer dresses, and the prices are very reasonable.

If you know you want something in particular and ask in advance they will take it to a roadshow for you.

Lovely daisies 

FMQ is really down to practice, practice and yet more practice.  I'm still only half quarter way there all I can do is squiggles or sqiggles and loops.

Has anyone seen the new 'Sew Today' magazine with free motion daisies down the front of a dress?

For any sort of support - cups or shelf - it needs to be held firmly against the body.  That's why a bra has a back to it.  Just tacking cups at the top won't support anything unless the underbust part of the bodice is held firmly.  Backless bras usually have back straps going down to waist level like this.

Or you could try adapting an existing bra by substituting a clear strap at the back like this.

Hi Elnnina
The buttonholes are done but they don't stand out and the buttonholer wouldn't take a second pass without jamming up - on less bulky fabric a second pass makes them look much better - so maybe I'll go over them by hand, maybe not.

I have seen all sorts of old and new threads.  I will buy something if I haven't seen it before, but sometimes an envelope just arrives in the post with a bit of cotton wound around a piece of card.   I've seen Strutts Milford Knitting cotton and Strutts Lustre knitting cotton and I've seen English Sewing Unity Glacé but nothing labelled as  Strutts Super Glace Gimp.

'Gimp' is one of those words which is a bit vague in definition - often it's a very round thread which might have a wire or thick monofilament at the core which is closely wrapped by finer filaments, or it can be a very firmly twisted 3 or 4 ply thread.  Either way it's firm and round. 
https://www.needlenthread.com/wp-content/uploads/2012/10/silk_gimp_02.jpg
In bobbin lacemaking a gimp is just a thick thread used to outline motifs within the design and is best if it's not firm, indeed  historically they sometimes just used several strands of the main thread wound as one onto a bobbin for use as a gimp.
http://gwydir.demon.co.uk/jo/laceold/exflower.jpg

PS, I've just read you PM, will answer in due course.