How to stop Spaces from taking me to an app’s Space when I open a new file

Stop Spaces from switching spaces due to an app coming to the foreground:

defaults write com.apple.Dock workspaces-auto-swoosh -bool NO && killall Dock

Or via the GUI: System Prefs > Spaces and then uncheck the checkbox at the bottom: "When switching to an application, switch to a space with open windows for the application"

Stop (slow down) Spaces from switching spaces if your mouse presses against the edge of the desktop:

defaults write com.apple.dock workspaces-edge-delay -float 60 && killall Dock

You can create a new service using automator (from the applications folder). At the top of the automator window, enter: Service receives 'no input' in 'any application'. Then, in the workflow, add 'Run applescript'. Make the applescript contain the following:

on run {input, parameters}

    tell application "Terminal"
        do script ""
        activate
    end tell

    return input
end run

(You can add any command you like into the do script line between the " " (e.g. something useful to run when terminal first opens like uptime if you like, or just leave it blank).

Save the service as 'Open Terminal' or whatever name you like. It should now appear in your services menu.

Then if you want to add a keyboard shortcut, you just need to go to System Preferences -> Keyboard -> Keyboard Shortcuts tab, select services in the left hand menu, and find your new service (its probably near the bottom). Just click in the space to the right of your service name, and assign it whatever keyboard shortcut you like, and hey presto! it should all work