This was hard stuff to come by as nothing seemed to be written in detail about it yet.
What I have discovered about Gas Harvesting...
Gas harvesting is a means to obtain the raw materials necessary to Booster production. Gas harvesting requires a gas cloud which must be discovered via Exploration as a LADAR site; typically you'll only find the right kinds of clouds in low sec / null sec.
Gas harvesting requires the Gas Harvesting skill which requires Industry 4 and Mining 1. The skill book costs between 36 and 40 million ISK. Each level of the skill allows you to fit one Gas Harvester I module. It trains fairly quickly requiring only 15 minutes at level one.
Each harvester module mines 1 unit of gas per 30 second cycle. The harvester module is considered a "turret" which prevents fitting the module on a Mining Barge which has no official turret slots. These modules seem to run about 9 million ISK each.
Each unit of gas (this might vary) is 10 m3 of space.
Gas clouds yield various types of "cytoserocin". Each type is a fundamental component of a different type of Booster. This should not be confused with "mykocerosin" which is used for Synth Boosters. Synth boosters appear to do the same sort of the things as "regular" boosters, but to a lesser effect and with no side effects--at least I didn't see any on Frentix synth boosters.
Gas --> Booster
Amber --> Blue
Azure --> Soothsayer
Celadon --> Exile
Golden --> Crash
Lime --> Frentix
Malachite --> Mindflood
Vermillion --> X-Instinct
Viridian --> Drop
Each type of cytoserocin must be combined with some other simple components like Megacyte or Water to create Simple Biochemical Reactions. This process requires a Medium Biochemical Reactor (POS). Once you have a reaction like Standard Drop Booster Reaction you can fabricate a unit of Standard Drop Booster.
Creating boosters requires the Drug Manufacturing skill. This skill costs 20 million ISK, but is generally only available in NPC 0.0 space. It will also require a BPO/BPC for the booster in question. As boosters/drugs are illegal in Empire, making them requires a POS manufacturing facility (Drug Lab). They will be confiscated by gate Customs Agents. BPO/BPC can be found in COSMOS complexes else they can be bought on Contract. Production of Boosters seems rare and thus the demand for the BPC's seems also low.
I did see a 1000 run BPC for Synth Frentix Booster in Jita for 8 million ISK. Each dose would require 17 "Pure" Frentix Booster (reaction). Each reaction takes 40 units of Lime gas... so 1 Dose of booster equals 680 units of gas. With 3 harvesters... that's 226 cycles... 30 seconds per cycle is 113 minutes or just under 2 hours of gas mining to get 1 dose.
Gas mining mission example: Like Drones to a Gas Cloud
Mine 425 (4250 m3) units of unusable cytoserocin AND kill all drones. There are only 4 waves of drones. The largest is cruiser sized (no battleship sized).
Award: 1.3 million ISK
Bonus: 1.3 million ISK
Standing Increase: 4.8% (will vary with your skills)
Recommendation: Start with a Battleship fitted with one or two harvesters and your favorite weapons. Kill the 4 waves. As you mine, remember to refresh your can. Alternately, after you kill the waves, swap to a hauler and AFK mine. Remember it takes 30 seconds per cycle... so 2 units per minute per harvester... 1 harvester means you're spending the next 4 hours mining gas.
My real recommendation is (even if you have these skills), just skip this mission. Complain about it loudly to CCP.