Sliding Hatch, Cover, and Teak board removal

[BobAthensGA]

Long story short but something fell behind the sliding hatch and the hatch cover and there was no way to get it out without removing the sliding hatch and cover so that's what we did. The long pieces of teak that go fore and aft are screwed onto the deck from below. There are 13 phillips head screws that go up from inside into the teak. The teak does have bung holes visible on top but the screws are from below. Once I got a putty knife under the boards and dislodged all the silicone I was able to lift up the boards. It took about 30 mins to remove all 13 inside screws, pry up the teak and unscrew the coach top. Took a couple of hours to really wash both and to clean out some really nasty leaves and such that was under the coach top and to remove all the silicone that was used to seal it.
A few things I am curious about and would like some ideas:
1)   The teak boards appear to have small blocks of wood that has been added to the underneath to plug the cavity that the bung hole covers from the topside. The "blocks" appear to have been made to fit flush against the bottom and plug the area under the bung. These "blocks" are not in good shape and will not give much for the screw to bite into. Any suggestions on what type of filler I could use to provide something for the screws to bite into? Wood filler or epoxy?
2)   The screws have the decorative ring washer at the head. I don't know what you call it. The PO filled around the head and the washer with sealant. This is great to keep drips out of the cabin and all the places they like to land (laptop, cell phone, pillow, etc) BUT it also doesn't let you know you have water going through a hole and past the core.  Is the core wood or solid fiberglass  in this area? If it is a wood core would it be best if I over drill them, add Rot Git, Epoxy and re-drill?
3)   The sliding cover goes under a coach top. Not sure what you call it. The coach top had a 3 inch wide layer of silicone going athwart ship at the forward most edge. The silicone sealed the forward most edge of the coach top. Is this the correct thing to do or should you leave this unsealed so that water and small junk can drain threw?
4)   The teak boards had a random bead of silicone going from end to end. I am not really a fan of silicone. There is lots of silicone that has been used on the boat. I am slowly replacing it with Butyl tape. I was thinking I would put some butyl tape around each hole that goes through the cabin top for about 2 inches around each hole. Is this correct? Would you put it anywhere else on the teak board? My thought is to only form a barrier around the perimeter of the screw holes and let the rest be open to drainage. This will also allow water to get under it but hopefully not down through the screw hole.  The only way to stop that is to seal all 4 sides.
5)   Sliding Hatch: I have sprayed Tri-Flow Superior Lubricant) with Teflon Aerosol ( type that into Amazon and you will find it on the sliding hatch. It eliminated the squeak and makes it slide much better. Reapply about once every 3-4 months. Put two or three quick squirts each side. It made a friends Hunter slider so slick he pushed too hard and fell down into the cabin. I ordered some UMHW Slick tape and will try it out. I HOPE that it will stick and stay stuck without coming loose and balling up on the track. Part of me says just spray it 4 times per year with the spray lube and don't get too fancy using the UMHW tape. I'll let everybody know how the UMHW tape works. In 6 months if I post again about removing the sliding hatch you'll know to just use the spray.
6)   I think the teak has Cetol on it. Has the more orange look and everybody on the dock said it's Cetol. I read that all you need to is to wash it good with dishwashing soap and some bleach and then scuff it up with a 3M pad. Put a couple of coats of the Cetol Light then one coat of the Cetol Gloss. Please let me know if you have other thoughts on redoing the Cetol.
7)   Traveler: did NOT have to be removed on my 1988 MKI