What john said...
As far as fuses vs circuit breakers are concerned, breakers are re-settable in flight. Fuses, not so much. That is why civil and military aircraft typically use CBs over fuses.
There are bus bars made for circuit breakers that make it easy to separate the different busses you might need, i.e. essential, main, and avionics.
Yes these are experimental aircraft and I am a fervent supporter of those ideas. However some aircraft based best practices are there for a reason.
As for switches, there are AC and DC rated switches. At low current (assuming 12VDC) there is no much to worry about. At higher currents you will be dealing with average voltage and arcing. Will any AC rated switch work? yes. How long? Who knows. It wasn't designed or tested for that.
I opted for NTE 12VDC 20A rated rocker switches. Are they "aircraft grade"? nope. but they are 12V DC rated switches designed and tested to handle 12VDC at 20A. Anything 20A or less should be fine.
Steinair has a great site. The site has pics of pretty much everything so you know what you are getting. I highly recommend steinair.com if you are unsure of what you need or just need to see what you are asking for.
For placards I recommend engravers.net. Very nice custom placarding and very reasonable in cost.