Just about to go to bed and checking in here for this stuff 
Tooling gel is the topcoat for production molds to produce an ultra hard high gloss finish on the mold for multiple pulls. To apply properly requires special TG spray equipment. It physically can be brushed on in small applications, but resulting qualities suffer. It is not a mold release. It is also not a requirement for a mold when making one or two parts, but something I used every time for consistency.
Yes I can produce these parts but one has to understand that the molds themselves of this complexity can top into the thousands of dollars(labor and material) to be rigid enough to pull multiple high quality parts from. You’ll have multiple-piece molds to incorporate the appropriate fasteners/latches, structural integrity, and ridgelines for factory seal capability. As a result it’s often not beneficial for one person to bear the brunt of the mold process and why multiple orders(IE group buys as most refer it) are required to cover the initial cost of the mold production with such parts.
In short I refuse to cut corners and do things half-assed, but the cost reflects. I’d really have to look at the car in depth to really have a graps on the actual part at hand and be able to discuss this with more certainty.
Yes resin infusion in general is that, but it’s a bit more complicated than wet layup. Small parts can be infused from one end of the mold but most require a spider feed. Resin must be fed from a pressure pot, and really must be degassed to eliminate bubbles. I have a large degassing chamber to achieve this. The benefit of infusion is repeatability, and from a production standpoint that equals money saved. For small parts and home scale stuff, wet layup is more than capable of producing quality parts.
I have no idea what you rig can handle. I have a few various 220volt 3/4-2hp twin and four cylinder vacuum pumps that i use depending on CFM required. Just because you pump can pull ~18+ inches of mercury doesn’t mean it’ll have the required CFM flow to pull the resin properly before gel time sets in. Most stuff you’d likely do I doubt you’d have too much of an issue with. Remember that too much vacuum can be bad as well where you achieve compaction and then proceed to remove too much resin from the laminate, resulting in a structurally feeble part.
Resin infusion does not mean you’ll have proper resin/composite ratio. That is a balance of knowing what type of resin to use with the laminate you’re working with amongst other things. Fabric weaves and weights layers of the laminate you’re infusing, temperature, resin viscosity, type of surfacing in the mold, etc, etc all dictate the what/when/where figures. What it really boils down to is experience with the laminates you’re working with. I’ve been doing this for quite a long time and have spent thousands upon thousands of dollars in wasted materials learning what I know now, and it certainly isn’t getting any cheaper. Pre peg is the only way to absolutely guarantee proper R/L ratio but is by far my most expensive application of my composite work due to material cost(in excess of ~$100 yard for some fabrics) and cost to operate the autoclave. I reserve this process for high strength structural parts like the suspension arms and larger components like the carbon cells for the small kit cars I have planned because you simply cannot get proper compaction of the laminate by vacuum pressure to get the strength required…
Resin is mixed according to manufacturer specs, but most MEKP’s are @ about 1.5% while most epoxies are around a 2:1 ratio(by weight). Again each mixed needs to be tailored to the specific composite you’re working on and the conditions it’s in(temps, etc). How much resin to mix is, yet again, just based on experience. Certain fabrics wet out very easy and don’t require a ton of resin to get saturation, while others like some of the insanely heavy 40oz E glass or kyntex biaxial required enormous amounts of resin for saturation.
Did I miss any questions there? I’m off to bed now.