Usually, yes.

Probably, but it depends on the amount you use.

that is approximately 63.5 grams

In recipes, generally one square means one ounce.

Yes if you prefer the taste.

125g = 4.41oz

may the baking sqaures be saved in the freezer if they near their expiry date.Does this reduce quality

The label says each square is equal to 1/2 ounce.

There is no set amount. Some pack may be small of 8 to 16 ounces, while large bakery packs may be as much as 50 lbs. of chocolate.

One is a solid and the other looks like a steamy diarrhea shite.

Baking chocolate generally contains more cocoa than chocolate produced for eating. Lindt does, however, make baking chunks, and some of their other bars are ideal for baking, like Lindt Excellent 70%

Yes, unsweetened chocolate can go bad in two ways:

1) Developing chocolate bloom (safe to eat, just unattractive)

2) Developing mold (Don't eat)

You will know instantly just by looking at it if either of these two problems has affected your baking chocolate.

Otherwise, baking chocolate will keep indefinitely, though it will lose its characteristic chocolatey flavor and scent over time, eventually becoming tastless (though still edible) after a year or two. For good results, it's recommended that you not keep baking chocolate longer than 6 months, for although it will begin to lost flavor sooner than that, unless you are a connoisseur or baking for a connoisseur, it's not very noticable.

The best way to store your chocolate, baking or otherwise, is in a cool, dry place away from heat or light. Storing in the refrigerator is not recommended as chocolate will absorb any nearby scents, affecting flavor. Additionally, refrigerating or freezing good-quality chocolate will negatively affect the quality of the chocolate, not to mention will most likely also cause your chocolate to bloom.