Whether it has anything to do with the two things you have noticed or not the mulching that has been done should not have been piled against the trunk. Which is buried so deep by it the root crown is not visible at all.

Otherwise one thing I would check for if it was my tree is this:

Armillaria root rot | UMN Extension

the white stuff looks like tree sap .. id call it pine tar.. but i dont want to start that argument in this post.. its not a pine... lol ... spruce tar i suppose ... could be indicative of boring insects ...

step back and give us a pic of the whole tree.. any construction around lately ...

i dont understand what you mean by bare spots ... on the trunk.. or all the dead branches ...

why did they die??... was any other tree removed recently.. etc ...

give us some history of the tree besides your description of what you are seeing ...

it might be easier to just take it down.. and replace it.. whats behind it??? ..hiding something??? .. im thinking it might not be worth spending a couple hundred on treatment or remedies... to end up with an ugly spruce anyway ...

btw.. all dead stuff ... that which does not bud out this spring.. is to be properly pruned out ... its dead ...

ken

ps: there is a conifer forum.. just for future reference ,. since they are also trees.. its all the same peeps in this case ...

https://duckduckgo.com/?q=spruce+diseases+in+nj&t=ffnt&ia=web