My fermenter has a spigot, but i only use it for drawing off samples to test with the hydrometer, which I rarely do anymore (during fermentation). Since buying an autosiphon, i have never used the spigot for racking over. I let it sit in the fermenter a good 2 weeks, then rack to secondary and steal a small sample of that to test. Then at least 2 more weeks in secondary, and it's surely at FG.
Rack to the Ale Pail, steal a small sample for the hydrometer, record. Prime, bottle.
The fermenter has a little doodad on the inside of the spigot that's supposed to be a sediment reducer, when bottling (kit said to do everything in the single container, and use priming drops). It works well, but the autosiphon works better. Since I bought carboys for secondaries, and an autosiphon, and an ale pail and prime with dextrose not drops, it's rather pointless now. The trub in my pumpkin ale was well over the spigot anyways.
Anyways, your bottle bombs are one of two things: the beer wasn't done fermenting when you primed and bottled it, or you over primed. Fix the first potential problem with regular hydrometer readings and patience. Fix the second issue with a digital scale to measure out the exact amount of dextrose to prime with. I even marked my Ale Pail with recommended priming amounts, right on the gallon marks. 1oz per gallon is easy to remember, but I also added the conversions to cups. It eliminates the guesswork, and it's kinda like a study sheet for a relative noob like me to memorize the amounts (for later in life when I'll undoubtedly not have to refer to said "study guides"). I marked my fermenter in much the same way, but because it's metric and I go by gallons. I also made a small mark next to the thermostrip, as a 'do not pitch over this temperature' mark. Again, not necessary, just added steps for quality control.
Try little things like that over time, to improve future batches, and don't let a simple beginner's mistake discourage you.