First is just a math operation. If you drag a pin off the Array Element or the Delay and type ‘+’ you’ll find it. Or type “float +” and there will be options for you.
Second, it doesn’t connect probably because the variable types are different. If you drag a pin off the Get and click “Promote to a variable”, you’ll get the variable of the required type. If you create a variable manually in the list in the left part of the window, you have to select the required type yourself. After you created any blueprint actor, its name will be available as a variable type, but you have to type in at least a few characters of its name to find it, because finding it in the list of types otherwise may sometimes be difficult.