I've always been operating under hte assumption that if my shield is down or somewhat depleted, I'm more visible. So I've been putting points into Advanced Shield Cap thinking it'll give me less downtime. Am I right in thinking this?
As far as I can tell the cloak works just as well, but the shield won't come back online as long as you're cloaked. Also, the shield will shimmer when it does come online, making you more visible, but of course you'll be uncloaked when this happens.
Nope. Shield and Cloak are two different things. The status of your shield does not change the cloak / visibility at all.
sheild will also shimmer when hit, which means technicly cloak works better when your sheild is down (though of course then you will die very easily if you are hit).