No, not per se. But an experienced numismatist can tell you by the date what the likely silver content is.
The melt value of Longines Symphonette sterling coins would depend on the current market price of silver. Sterling silver is typically composed of 92.5% silver and 7.5% other metals, so the melt value would be calculated based on the weight of the silver in the coin. To determine the exact melt value, one would need to weigh the coins and then multiply the weight by the current price of silver per ounce.
They're at least worth their weight in silver.
If you are interested only in the silver value, not all Halfcrowns were made from pure silver and the post 1947 coins contained no silver at all. Whatever the going rate for silver is. If you are interested in the collector (numismatic) value of the coins, please provide year and condition of the coins.
With no rare dates they likely are only valued for the silver.
All forms have value as silver metal, but coins may have additional value as a collector's item. Their worth, weight and purity is already known and does not need verification.
No, for silver coins as the value of silver changes the value of the coin changes. The same is true for gold coins.
Europe was on the silver standard from about the middle of the seventh century. Coins had no abstract value, rather they were valued by weight. A pound of silver was really a pound of silver coins. The smallest unit was some variation of a denarius.
They are sorted by size and weight. Coins that are too lite or misshaped are spit out in the reject tray.
In order to determine an estimated value for a roll of American Silver Eagles the dates of the coins would have to be known and if they were mint state [uncirculated] coins or proof coins. American Silver Eagles all have the same bullion value but each has its own numismatic value as well.
If you have a US silver dollar with a date of 1906, I'm sorry, you have a counterfeit coin. The US Silver dollar was not minted in 1906. Some of these are actually silver coins, and may have a value for the weight of silver they contain, but they are not collector's coins.
With those dates, the coins are Silver Eagle bullion coins that are made from one ounce of silver and value is whatever the spot price of silver is at time of sale.
It depends on how much silver is in it. Casinos use a multitude of different sizes of coins. Take your silver coin, find the weight in troy ounces then multiply it by silver spot price (at the time of writing it is $29.30). Casino coins have very little collector value and any value comes from the silver content in the coin.