1989 Bass Tracker Pro 17V drain/inlet holes?

[ScottyD]

New to the site here, but I've been reading up on alot of useful information and thought I should join because I'll be picking your brains on a restoration of a 1989 Bass Tracker Pro17 V.

I would rather not sink the boat when I drop it in for the first time, so my first question is to ask: There are 3 drain / inlet holes at the back of the boat shown in the picture - the one on the far right is the drain plug, but what are the other 2? The one on the far left appears to be a manufacturer install for the livewell inlet?? But the one next to the drain seems like an aftermarket job. Any ideas?

The boat has one livewell with 2 holes in it, one up top and one at the bottom. I assume the one up top is for pumping fresh water in, and the bottom for draining. Second question: Do I need to use a plug to keep water in it? Or does the setup keep the right amount of water in there while on the lake?

Again, thanks in advance for your help here..