Need help

I'm working on something I'm not sure which way to take it yet. I am interested in space travel and have a (rough) idea of either a story, video game, or animated series. 

For reference, I work in a very hands on, practical field and do not have a great understanding of science, metallurgy, or engineering but have a basic knowledge and have researched a fair amount. Forgive me for any dumb questions, as I'm considered an expert at work...but my work is not in this field, hence it being kind of a pet project/hobby. 

I want to create something where in the not so distant future mankind is able to farm a fuel that acts as a stable space traveling agent. Stable and potent enough to reach a (made up) speed I dub Earth Sun Rotation (ESR) or 67k miles per hour (107826.05kmph). ESR would become the official base speed measurement for space travel, i.e ESR 1 = 67,000 mph. Given that 67k mph is fast for us now, but very slow for space travel, improvements would be made to go faster, hence ESR .01 would now be 67,000 mph. ESR 1.0 would be 6,700,000 mph...this would of course increase etc until close to light speed where I'd have much disposition (fear of what would happen if going past light speed etc). 

I need help with, and it doesn't have to be rooted in exact science (but close enough to seem plausible): 

1. A material that could be mined from our solar system, creating a fuel that allows ESR speeds. A simple google search (forgive my lack of actual research) says: The gas giant planets in our solar system, Jupiter, Saturn, Uranus, and Neptune are considered to be primarily composed of a gaseous state, although their interiors contain a mix of gases and liquids under immense pressure.  

     - with ESR speeds these could be mined and the mined liquid would result in (fake name of super gas), I chose Malentium. 

2. A strong material that could coat space ships like a spray, or a material that could be infused with Graphene (Earth's most durable material) to allow for such fast travel (asteroids would cause no damage with this made-up material added to ships). I chose the name Adiseen. 

3. A weapon that can fire projectiles faster than 67000mph, and penetrate the aforementioned Adiseen coated armor to stop asteroids and space debris. (Armor Piercing High Explosive projectile)...(I want to stay away from lasers as that would be to advanced).  Even a rail gun only shoots about 5k mph. With the vastness of space, slowing to 67k mph would seem slow...but that would be the 'battle' speed. 

Thanks, this is a work in progress and I'm also working with some people on Reddit to develop concept art. 

Edit: I'm not looking for something like The Expanse realistic (if it is), or if Neil deGrass Tysone finds it perfect, but to where the average person enjoys it and someone in the space field would appreciate some correlation to realism. I.E. They never reload their firearm vs take cover, reload, then get back into the fight. 

Not in space or engineering, yet a long time scifi enjoyer. 

I am confused why ERS is 67k but then ERS 0.01 is 67k as well. 

As a scifi reader/watcher/listener I am not too fond of the deus ex machina "outside the periodic system" super material that magically shows up and solves all space faring issues trope. I rather have a black box "something something graphene something" explanation that hints at some fancy stuff done with the building blocks we already have. The mystery material trope only is worth it if you make the material really central to your story like the spice in Dune. 

Adiseen or adisene? The latter is more in tune with real names. 

A gun mounted on a ship will always carry the momentum automatically. So a gun will always fire a projectile that is movement speed + gun propulsion speed fast. So that is not an issue. Every basic pew pew will be able to have projectiles faster than your ship. Things will get wonky though when you approach speed of light. Stephen Hawking taught me that. Just use your ship's momentum to increase railgun speed. That just means piloting will play a big role in your space combats which will be good for action scenes tbh. 

Thanks for the reply! All good suggestions and I really like Adisene as well as incorporating what we already have with a mineral mined from elsewhere. Appreciated 

1.  The most realistic materials to "mine" as power sources would be Helium-3 and Deuterium, which are the two most common fuels for fusion.  The most abundant source of these would be in gas giants, but Helium-3 has been deposited in the moon's regolith from eons of solar winds.  Other moons may have these deposits for the same reason, though further from the sun, the much less there would be.  Helium-3 would not be a liquid unless it's cooled down to almost absolute zero.  Deuterium could be kept liquid for ease of storage by storing it in the form of heavy water or deuterated hydrocarbons, which would then be isolated right before using in a fusion reactor.

On the more speculative side, a miraculous chemical isotope that is extremely stable but undergoes nuclear fission reactions with just a little prodding would work.More extreme could be some material that can become antimatter through some special physics.  Most regular chemical reactions aren't energetic enough to use unless you are doing a carefully pre calculated trip.  Lots of maneuvers or changing course etc would require way too many fuel tanks of conventional materials.

2.  The risks of running into asteroids are actually pretty low under most circumstances.  even the asteroid belt is not the usual thick minefield of rock generally portrayed.  concerns about hitting asteroids would not be the central concern about traveling at extreme speeds.  There are 'micro metoerites" that hit satelites and the space station etc, but a centimeter or two of steel would be more than enough.  If you're worried about larger sorts of impacts, a spray wouldn't get you far because it can't do anything about the momentum of a large rock.  Having the armor of choice be refered to as a special alloy with tungsten or iridium/titanium etc would do the trick

3.  I think guided missiles would be a very popular weapon in more realistic travel because if a railgun weapon has a travel time of several seconds before impact then evasive maneuvers could dodge, but a guided missile could keep on target for those.  There are a lot of talk about particle cannons where you fire a stream of charged particles which is is similar to a rail gun but with a much smaller mass at significantly higher velocities.

if you want it to be science realistic you should be using metric units instead of legacy imperial.

Micro meteorites would be an issue if you're fast enough. That's another reason why warp bubble drives are cool. But those would be too high tech for your setting I assume. 

I like the antimatter idea of windyrockbell. That's exactly what I mean. Some physics sorcery and mundane stuff turns into the material you need. And having enough energy for fancy space battles would be cool. Without some deus ex machina magic material.

Edit: and i very much agree. Use metric units. Imperial has no place in scifi for a good reason.