EFI, electric gauges, fan etc all running on a 63 amp here - no problem at all. Gauges will only draw 1-2 amps max. EFI itself including injectors will be <5 amps, fuel pump max 10 amps, but under normal load they pull <6 amps continuous. You aren't adding much extra load with EFI in reality. Most modern cars with ABS, EFI, Stability control, Heated front and rear screens, heated seats, AC etc will have a 110amp alternator at best. Your current 100A alt will be just fine.
No. The alternator supplies a constant, regulated voltage. The amp output on the box is the rated output- i.e. how much sustained current it can handle without dropping voltage and/or overheating. FWIW, my 2006 Acura TL that has all sort of electrical gadgetry uses a 130A alternator. I think you should be fine. HOWEVER, you will be testing the limits of the V-belt at 100amps, should the system need that (e.g. lower RPM, start with low-ish battery charge state).
Sorry to be an anal guy, but I'm pretty sure your electric water pump takes more than 5 amps: "The pumps from Meziere and Moroso all draw from eight to 12 amps under continuous use, while possibly spiking a few amps higher at initial start up, which is the case with many electric motors." From an informative article about water pumps: http://www.lsxtv.com/tech-stories/f...t-you-should-know-about-electric-water-pumps/ Again, sorry to be anal about such details. It really doesn't matter either, because as everyone is saying, 100 amps should be plenty for the OP.
Mine's a Proform. I was sure it was a 5A fuse, but remembered once I saw the specs it's a fusible link, but listed as 5A draw (only 35gpm compared to 55 for the Meziere I saw). But I'm sure it does draw more on initial start. http://www.summitracing.com/parts/pro-66225bk/overview/ Todd I don't forsee any issues with the V-belt, but I'll find out pretty quick. haha I have a custom-fabbed low-mount bracket with precise adjustability for the tension.
100 Amp Alt should be enough with a single electric fan. The fan, fuel pump, and lights are going to take the most juice. I used to run a 63Amp and it wouldn't hold 12v when my dual electric fans kicked on. I now run a Powermaster 150 amp. and with an underdrive crank pulley it idles at 900rpm at 14.4V, when the fans kick on voltage drops to 13.8V... Running FAST EFI, MSD Digital 6AL, Spal dual fans, Holley Dominator Fuel Pump.
You should be fine. I'm running all that you described except the electric water pump and my system runs great.