Commissions are completely unnecessary if you just take a bit of time to go trading. I was able to make ~10m within the first year, starting from a Wolf start just by trading, mostly shipping supplies, armaments, and drugs to pirates and pathers. I'm willing to bet that trading earns 10x whatever your commission would earn, and IMO trading is too strong right now.
#1 That depends on rng of excess and shortages occuring
#2 You are still depending on the 1st of 3 years of free money
#3 You are doing nothing but trading for 1 year
#4 That is a specific playstyle that doesn't do missions or anything else inbetween
#5 It sounds like you are talking about the last version of the game and not .95a, the market is more stable now reducing profits... making this entire post based on out of date information and not "right now"
#1 is a guarantee with certain markets. Pathers will have a constant shortage of supplies and other goods, allowing you to sell for no less than ~160 per supply (low access due to hostilities with other factions means that they cannot import enough of anything really). Any trade disruption or pirate activity will raise the price further. I was maybe a bit lucky to have Pirate activity in the Pather's system for several months. Pirate trade fleets are far and away the most common trade fleet to die, meaning pirates are most likely to run into trade shortages. Umbra in particular struggles a lot with trade fleets due to the number of Diktat patrols in Askonia. Easy money buying excess volatiles and selling to the (near constant) shortage in Sindria. Even if there isn't a shortage, you are usually buying the excess Volatiles at 100 per, and selling at 200, for a quick cash in. Lobster is also quick cash, as any place facing a luxury good shortage will generally buy them at 200+, when you buy them for 80-120 after tariffs (worth picking up the ones on the open market).
#2 The total stipend is 12 * 15000 = 180k. That's not a lot in the scheme of things. Yeah, it's helpful getting going in the first month so you can get your first Buffalo. I did do a little bit of combat at the beginning, fighting Pirates around Garnir with the initial Corvus system bounty, but after I had enough to get a Buffalo, it was time to head out with a pile of stuff (IIRC I loaded up on Supplies and Marines, and ended up burning a SP to disengage from some Pathers who got aggressive when I tried to sell them stuff). After your first 'real' trade, you are usually sitting on like 50k or so, which is enough to start covering a lot of shortages.
#3 Sure, except I'm also shopping for weapons and ships (by the end of it I had a bunch of cash, a fair bit less than 10m, but 2 Conquests, an Atlas, 3 Collosuses, an Eagle, a XIV Falcon, 2 Tempests, a Prometheus, a Phaeton and an Apogee, and some random destroyers, plus an acceptable collection of weapons (shopping for HVDs, Maulers, Needlers, etc). Basically, I just skipped all the early combat and moved straight into the 'early capital ships' stage.
#4 I mean... what missions are you talking about? I'd take advantage of procurement and hauling missions, and various bar events for ships (bought the Eagle and Atlas, raided for the Falcon)
#5 The market is hardly more stable. I was on RC11 or RC12 for that particular game. As mentioned before, there are guaranteed shortages of supplies, fuel, marines, and drugs on Chalcedon due to insufficient access. You could call it a bug, but it's the system performing as written. Pirates and Pathers face high access penalties due to being hostile to most of the sector. This means that they can't import/export enough stuff, so they face shortages and excesses everywhere.