Silver In Ingots Or In Circulated Coin

National currency is always recognised as guaranteed purity to whatever level that country was making at the time of issue. Homemade ingots have no recognised reliability of purity or content. Look at it in this light....even in the Philippines you would be comfortable buying pre-65 U.S. coins as you know they are 90% silver...but let's say someone offered you a bunch of Ivory Coast "silver dollars"....how would you know the actual ( if any ) silver content if those coins without research on your part. Now take it a step further....someone offers you a bunch of "People's Republic of Atlantis silver dollars". You have no way to research these at all ( like homemade ingots )... so unless you pay to have them assayed....you can't know what the silver content is. So you either have to pay ( handsomely at that ) to have an assay done....or rely on luck. Always go with the path of least confusion....certified and recognised silver is always the best way to go.

Eh, Weight and volume doesn't change much, so I would leave as is.

Yeah, considering all the fake silver and gold stuff that is out there these days, anything that improves your authenticity would be a plus IMHO. I would leave the coins as-is. The only metal that I would be tempted to melt down would be scrap jewelry, dental gold, or other odd sized silver or gold.