There is no evidence in the public realm - yet. As investigations continue, including by OPCW over the next fortnight, it'll become clearer.
Genuine question: would you be content if all the information was now released for your pleasure and subsequently that stopped any criminal trial?
All your other questions I've pretty much gone over on at least one occasion. And no, my judgement is not based on simply the government's spiel.
No 'evidence in the public realm - yet'. I've heard that one before many many a time. Only for it to be bull. Weapons of mass destruction springs to mind, 'we can't tell you everything but believe us'. Or evidence that was so 'cast iron' it showed their guilt, only to be overturned due to miscarriage of justice. Not all 'in the public realm- yet' but some selectively put in the public domain to give the impression of guilt.
Criminal trials are brought with much more 'evidence in the public realm' being released than you seem to be implying with this case. There have been many criminal trials that have taken place with 'leaked' evidence by this or that person to show the person or persons is/are 'guilty'. The media have been allowed on many many occasion to release information that shows the guilt of someone. That evidence, along with other evidence, is then presented in court and people found guilty only to be released due to a miscarriage of justice. As you well know.
In this case a trial wont be stopped no matter how much 'evidence' is released because all and sundry knows 'Putin gave the orders and it was carried out by one of his mates'. A Russian is guilty even before a trial has begun. All the state will do is find a connection between Putin and said person or persons. Maybe riding bare-chested on a horse. It will be that smug and sarcastic.
Evidence is selectively and deliberately released to point the finger of guilt. As has happened on far too many occasions. Selective evidence is released to attempt to lay the blame of guilt on someone. In this case to ratchet up the war, war against a person who has fallen out of favour with the west, because he wont allow the US to do what it wants, in particular in Syria, and is now deemed an enemy. The parallels with Saddam Hussein are all to evident.
'Released for your pleasure', really. Weapons of mass destruction and the 45 minute launch was used to justify invading Iraq and the death of hundreds of thousands, if not over a million, and a country destroyed. Egged on by the house of commons, with the exception of a handful of people, including Corbyn. Isn't it a pity that we all weren't privy to the information Blair received so that we could make up our mind and put pressure on the warmongers? Very much like now. The government want to ratchet up the war,war against Russia and they want us to blindly follow and shout 'go gett'em Boris'.