pretty accurate guide for skills as you got everything down that you need to know the basics for; as for what Pause() does, it just tells the game whether or not to pause the queue of what code to run when currently in an event scene (mainly so it doesn't try to run multiple things at once)
do note though that some flags are currently unfinished / non-functional / require extra code to make them work properly, so I'd say stick to what's currently used by other skills when making something of your own
attacks are pretty simple since you mainly just need to worry about setting up a listing for them in AttackList.cs; once an attack is ran, the actual code for the attack is stored in EventScene.cs (match the internal id value of the attack to the case number there), though there are some special cases like digest that don't use the event system since they use a separate system to handle their functionality
attacks use this format at the top of a listing: attack id value (make this unique) > display name > internal name (put whatever here as the player won't see it) > description > power > en cost > stun amount > minimum range > maximum range > accuracy > array size (make this value equal to the amount of flags you put for the attack) > flags (look in Attack.cs to see what you can put in here)
most of the code you see in an attack listing is mainly for controlling values in the ui / controlling the conditions for which an attack can be used, so I'd say just copy an already-existing attack and modify that