Need Help With Utter Dome Using Fixed Magic

[Pentaclegram]

Hello again everyone! I'm having trouble puzzling out the interactions of limitations and enhancements with Fixed Magic, and I was hoping some knowledgeable stranger could shed some light on the situation. I would appreciate any help that anyone can offer.

I'm theorycrafting a Super character who uses Gravity as their power, and one of the abilities I had in mind was a completely impenetrable spherical barrier that could be used as an impenetrable defense or safe haven for a small amount of time. I was having an immense amount of trouble finding something suitable in Basic or Powers. The Utter Dome spell seemed perfect, though, and while googling I came across the Fixed Magic system from GURPS: Fantasy.

I initially built the spell as a power using the formula provided, where 14 was the prereq count, M2 was required, and points for the level of skill I wanted (14) was 4, which gave me a final point total of 14+5+4+4, or 27 points to cast a 1 yard radius Utter Dome with a cost of 6 fatigue, 4 to maintain.

Question 1: One of the issues I'm having is how to handle the Area of the advantage. Should I build the advantage as if the spell had been cast with a larger area, by using the Area Enhancement in Basic, or can I choose? Utter Dome has a base area of 1 yard, and I wanted a 4 yard radius (or so). Building it into the spell pre-conversion increases the fatigue cost but not the point cost (directly; indirectly, my character would need to buy Costs Less Fatigue to be able to afford it), while building it with the Area Enhancement does the opposite. Using the pre-conversion method would end up costing a lot more points because of the Reduced Fatigue Cost necessary to make it usable for more than a few seconds; approx. 400% compared to Area's 100%.

Question 2: Speaking of fatigue costs, Utter Dome as an advantage essentially has Costs Fatigue built into it, but designed for a duration of 1 minute. The plan was to use Reduced Duration to knock the duration down to 1 second. Costs Fatigue is a -5%/lvl limitation for a 1 minute activation, and -10%/lvl for a 1 second activation. How should I approach this? Building an unmodified Costs Fatigue/second into it seems like it'd be stacking with the already-included fatigue cost, but leaving it unmodified feels like it's not scaling properly. Is this simply how Reduced Duration is intended to work, and already built into the cost of the limitation?

Question 3: On the topic of duration... I wanted to be able to do something like block Dr. X's kaiser beam with Utter Dome using the Reflexive enhancement, maintain the 'spell' for a few rounds for VFRegeneration to kick in, then end the effect right before the start of my next turn. With Reflexive and the duration reduced to 1 sec, turn order becomes a bit trickier. Do I need to wait out the full duration of the effect for it to end, i.e., it ends on his turn, or can I end it prematurely through an enhancement? If so, where can I find it?

Question 4: Fixed Magic is, by default, magic(al), as in, requiring a mana field. My Super uses a Gravity Power Modifier worth -10%, and I'd like to replace the magical requirements with the ones I'm already using. I was thinking since the Magical modifier from Powers and my Gravity modifier are both -10%, I should be able to swap it over to Gravity as a -0% Limitation. Would that be the correct interpretation?

Question 5: Utter Dome has the standard casting time of one second, and after the cast takes an additional one second to form. Can I get around this with two separate Reduced Time 1 enhancements, one for each duration? Or, by RAW, will Reduced Time only affect the casting time?

Well, that seems to be it. Thanks for hanging in there! I apologize if the format makes it seem like an exam; I promise your answers will not be graded!