I've always had good experiences with Meyer, another chicken friend swears by Mt Healthy.  Both good small to medium small Ohio companies. 

In normally chilly spring weather, usually just good boxes and shared body heat, (which is why there is a 'minimum' order in nearly all cases) as well as responsible mail handlers and carriers who keep them indoors while transferring to other trucks and such.  In winter nowadays, most places put a chemical heat pack in the box with them too.

The post office will call you as soon as they come in, and you will need to go to the post office to pick them up.  I always go to my local office and let them know that day old chicks will be arriving within a day or so of the planned shipping date, and again when I get notice from the hatchery that they have actually shipped.  I live in a rural area where they are very used to the chick boxes coming in the spring to farmers, and there's no doubt which post office is 'mine'.  If you live in an area that could have more than one post office, I'd make EXTRA sure which one is the correct one and give them plenty of warning, leaving your phone number and any pertinent info.  Most hatcheries also make sure your phone number is clearly on the shipping label too.

Our PO calls me at any horrible hour the truck arrives on their loading dock, because they know that's what we 'chicken people' would prefer… some wait till 9am or whatever. 

I think there's a place for either type of bird, the amount of meat and the size and texture and such from the cornish X's is more like what we're used to from grocery store birds, though, if you pasture raise them and give them more room to move around more, chase bugs and eat lots of grass and such, the meat will be much better tasting and better texture IMO.  If you leave them locked in an indoor pen and eating only chicken feed with no incentive to move around at all, it will be much like you're used to from the store.  It really is possible to raise them so they're at least a bit more active and eating grass and such.

That being said, I still prefer the meat (and broth) you get from the dual purpose birds. 

As far as the size/brand of a solar fencer you'd need, I don't have any experience with that!  I'd see what the fence instructions say and ask someone at my hardware/feed store myself.