[tartuffe]

I'll try and help on the first part. When the drains from your splashwell out your transom are below the water line, the deck drains are right at or just below waterline. There is nothing more than a curved tube going from the deck drains to the splashwell. If you are getting alot of water in your bilge one possibility is that those once flexible tubes are brittle and cracked or you may have leaky connections. Mine tend to leak at a fast drip.

Not sure how clear that explanation is but your deck is maybe 1" or 2" above the waterline. Add couple people and gear and you are just above the waterline. No check valves to prevent you from getting a very wet deck.

My automatic bilge is straight wired to the battery. I like that as low as I can get it but others may object. Any water that gathers in the bilge is only making your hardly effective deck drains less effective. I like my manual bilge equally low if it will fit.

The trick is mounting both. There is only a piece of wood maybe 8" x8" glassed into your hull for this. Any other area and the glass is not very thick.