... but this means i can use regular old urethane? i was wary of doing this for concerns that it might be poisonous.
Once it has cured, it is not harmful. While it is still wet, the oil based varnishes have volatile organic compounds (things like mineral spirits and naphtha) that evaporate as the finish is curing. I suppose that you could even avoid most of them by using a water based varnish.
I am not a big fan of film finishes (varnish, lacquer, shellac) on wooden bowls and other treenware because it won't be long before microscopic cracks will develop as the bowls are used and go through many cycles of expanding and contracting from heat and moisture. Once these tiny cracks develop, it allows more moisture to get into the wood and accelerate the process of cracking. This leads to the possibility of bacteria getting into the tiny crevices which could be a problem if food were left in a wooden container long enough to get a culture going (which might not require much time for something like shrimp gumbo). The solution to this is not difficult -- wash the wooden treenware thoroughly and soon after use, not days later. Also, do not store leftovers in wooden bowls.
... also, with going with the bare wood, does it change the flavor of the food in it, and can the bowl be stained and then left bare or would that be a bad idea.
For treenware, it is best to use maple and other non-flavorful woods. There are some oily tropicals that can impart unpleasant flavor, not to mention a few poisonous organic compounds that exist in the wood to keep pests from attacking the tree while it is growing.
Most definitely do not stain wood and leave it bare. Wiping stains are meant to be covered with a film finish. Since the stain sits mainly on the surface of the wood (penetration depth is only about the thickness of a sheet of paper), it will eventually wear away and become an ingredient in your porridge as well wearing off from washing the bowl. Besides that, you might not like the taste. The same thing applies to dyes which penetrate a bit deeper into the wood -- and, many are water soluble.
... i saw on a video somebody using mineral oil, another using tung oil, and a third using linseed oil. are all of these safe to eat from, or do they have to be special versions of the oil?
There are several types of mineral oil, but the kind found at grocery and drug stores is a paraffinic oil. Mineral oil is a mild laxative. I grew up at a time when kids were given a does of mineral oil at regular intervals just to keep their systems "purged". Mineral oils have been in the ground for millions of years and have not dried yet -- there is no reason to expect that it will dry any faster in your wooden bowl. Why people use it is beyond me, but that is their business. I use mineral oil on the leather honing wheel of my Tormek sharpener and that is the extent of my mineral oil use these days. Even so, I still cringe at putting mineral oil on the leather. However, there are worse things than mineral oil -- for prompt action, nothing beats caster oil.
Tung oil, linseed oil, and walnut oil eventually cure, but it may take several weeks before they fully cure. I like them because they are easily renewable and look nice. They are not nearly as durable as varnish, but it is easy to freshen up a bowl with a coat of oil.
I generally use pure tung oil or walnut oil. Pure tung oil is quite costly. The walnut oil that I use is found in the grocery store where you find salad dressing. Walnut oil has a pleasant aroma. You can also make a wonderful balsamic walnut vinaigrette with the walnut oil and balsamic vinegar.
I do not like linseed oil because of the smell.
Whatever oil you use, allow time for it to cure so that it does not get washed out of the bowl as quickly.
I do not know if there is a problem with using spalted wood for treenware other than the fact that the wood is in the initial process of decaying and therefore could have softness that allows it to absorb stuff more readily. Turning spalted wood is hazardous to your respiratory system without adequate breathing protection. I have no idea if there is any issue with the digestive system, but spalted wood can also contain claustridius, the bacteria responsible for botulism.