Hello and welcome to the forum.
Is it okay if this plant stays indoors year around? (I read both yes and no)
I have a strong preference to get all of my tender plants outside during the summer. I feel that they really do much better and it is easier on me. But with cool weather almost upon us you might as well establish it in its winter quarters right off the bat, no point in moving it around more than necessary. You will have all winter to decide what you wish to do with it next summer. Apparently Fukien Tea is able to do well with moderate lighting, I don't grow this species so I will defer to others.
Make sure to explore the rest of the first two sites, they will answer most, if not all, of your questions. The second one in particular is oriented toward indoor cultivation.
Watering? (I read many different versions)
Have a look at the sticky threads located at the top of the forum, the one on general growing has tips on basic watering. Briefly, water thoroughly from above then wait (as appropriate for the species in question) before watering again.
Feeding? (Could I use Miracle Gro? If so is there a certain kind?)
Most bonsai can be fertilized with general products with no problem, no need for the so called bonsai fertilizer. I am not aware of any special requirements with this species.
Whatever type of fertilizer you are familiar with will probably be OK as long as you don't over-do it. I mix my fertilizer at full strength (dilute as per the instructions on the package) although others prefer to mix at half strength. Whatever you do do not mix it at more than the suggested ratio.
Should I set the tree in a few inches of water if I was to go away for a week? or all the time so it always as water?
Standing your pot in water does not sound like a good idea to me. Some species tolerate, even prefer, this technique but I don't think Fukien Tea is among them. Your pot must drain freely this is why bonsai growers are so adamant about using coarse, granular soils.
Vacations will likely be a problem fortunately, or unfortunately, I don't travel much so I am able to tend my trees. I can't really help much there.
Some of the other members probably can be more specific than I was able to be.
EDIT: See the third link posted above.