Rigging a Fiberglass Boat

I will be rigging out a fiberglass boat and wanted to hear any tips from you guys. I tend to not like asking for directions but in this case I'll take all the advice I can get and do it right the 1st time. I would like some comment on the following

1. Drilling without cracking the gel coat.
2. Backing material for rod holders and downriggers
3. Drilling through the transom to run transducer/speed lines to graph
4. Electric downrigger hook-up. What electrical connectors do you like. I'm thinking a flush mount outlet for each rigger on the inside wall of the boat. It has a fully molded back so I will have to drill access holes to run the wire to the rigger.

Pictures would be great but any words of warning is what I'm really looking for. After re-rigging my Alum. boat 3 times in 3 years, I've learned a bit about where I want to mount stuff but really want to do this once and be done with it. Thanks in advance.