I'd like to start by making a distinction between the Scottish government and Scottish public. As you said, only one MSP voted in favour of Trident. But the Scottish public are more balanced, with slightly more in favour than not. The Scottish government are presently dominated by the SNP, who have been anti-nuclear since their inception. Initially they were against both nuclear weapons and power, but that's changed recently. Now they are still in favour of making Scotland free of nuclear weapons, but are willing to make concessions with regards to nuclear power.
As the SNP argue it, nuclear weapons are a dangerous irrelevance, and defence jobs have been cut in Scotland overall, so Trident is an exception to the rule of money being funnelled out of Scotland to Westminster, which is taken from causes the Scots feel passionately about (social services) to fund expensive projects they do not feel benefit them, like Trident. Though the money involved in terms of the UK is very small, in Scottish terms it's still a lot of money.
The counter argument made by the Conservative party, and most of the Labour party, is that 12,000 jobs in Scotland which are directly or indirectly tied to Trident would be gone without it. But after closer examination it seems this figure is inflated. The real number being closer to 500, after the Ministry of Defence was asked to clarify the number of Scottish jobs specifically related to Trident.
As for the question of where the navy would move it... a charity called Save the Royal Navy has a website, which puts it bluntly in an article titled Why Relocating Trident is Virtually Impossible. It's an interesting read, but the short of it is that no other places in the UK are as safe, secluded, or viable. This is an opinion presumably sourced from the Ministry of Defence's saying as much:
Neither the Devonport naval base nor the Devonport dockyard, which is
owned and operated by Babcock, safety case permit the berthing of an
armed Vanguard class submarine
Other possibilities suffer from various issues, like being too shallow or popular with tourists. The only real alternative might be sharing a base with American nuclear submarines in the US (French submarines are smaller and have no hardware in common).
As for the question of the forms the nuclear deterrent takes, presently it is just the Trident fleet of four submarines. Before submarine missile technology was purchased from the Americans in 1962, Britain operated a nuclear bomber fleet called the V Bombers. There were three bomber designs; valient, victor, and vulcan. The latter being the most iconic and famous. Famous because the delta wing design was revolutionary at the time (it took American industry a while to catch up with the B2), and for a bomber it had great manoeuvrability; most uniquely that it could barrel roll. The vulcan was finally retired in 1984 after its use in the falklands war, but had been obsolete for over a decade prior due to developments in Soviet missile technology, which is part of why submarines were preferred (also that you can't preemptively hit them like you can an airbase). To my knowledge Britain has never had nuclear silos, and has never deployed tactical nuclear weapons as the Americans and Russians did with various sorts of artillery and mines.