I'm sure there are going to be people who are going to tell you why your wrong starting out this way and that you should consider doing it 'a better way' but I'm interested in others answers to the actual question you put forth so I'll attempt to answer your question based on what I know.
I've been in this business for a long time starting out as a PA and worked my way up through each department except for makeup and wardrobe. I mention this because its how I can keep costs down because I know how to do each job or fix most problems that come up (obviously there are exceptions to this, I'm mainly talking about small promotional videos). I feel like this is crucial for starting a small production business because costs mount quickly, the more you know how to do, the less people you need to pay to fix a problem.
Find a great editor and pay them well. Great editors are extremely hard to find. Great editors can fix (within reason) poorly produced wedding/promo videos. I usually pay depending on the length of footage and the turnaround. So for a 3-5min promotional video of no more then 3 cameras, combined with less then 70 GB total around $250-450. This is low, most editors charge hourly. Hire a great DP. For most experienced videographers/cinematographers/DPs who also grip/gaff their own shots (meaning they own their lights for small promotional videos and interview style lighting) charge $350-$450/day. I usually hire one person at this rate (me) and then hire 2nd & 3rd camera operators around $150-$250/day. Sound op's I try to hire the same person $250/day. I hardly ever rent anything so these are pretty much all of my expenses which I do my best to film everything within one day for a 3-5 minute piece. So with an added 10-15% added for incidentals, my gross expenses are around $1100 low end (assuming I'd be DP'ing) and $1900 (I'm strictly producing, not DP'ing).
I truly believe in paying people what they deserve and I try to work with the same people each time. I'd rather not say how much we charge the client but I'm sure its easy to assume given the above.
Regarding training, google and youtube are your best friend IF THAT IS ALL YOU INTEND TO DO- meaning, you aren't going to go to film school or get an apprenticeship or start as a PA. Actually DOING it is much better, even if its only you practicing on your own. Like the guy said above, hire someone who knows what they are doing for your first 10 projects (not permanently) and you will learn far more then something you saw online. You will easily forget that amazing video you watched a year ago while half asleep on your laptop. You probably won't forget that 16hr day with 7 setups in 2 locations and what it took to get that amazing shot with 1K at 45 angle 9ft up 12ft away, a reflector 3.5ft away for fill and a 300w pepper for hair light with only 20 mins to setup- that will stay with you forever. However, if you'd rather go the online route then make sure you become a member of sites like these, Roger Deakins has one and of course, The ASC (friends of The ASC is even better, great videos and resources there). There are MANY other sites out there that have great advice, these are just some I use regularly.
Regarding cameras, lenses and lights- there are far too many to say what is the best. I have Canon C100's/C300's a bunch of lenses and lights I've gathered over the years. Arri have great starter kits and also look for photography lights to fill in the gaps, they tend to be cheaper because they sell more of them. Lowell for instance, has many starter kits at reasonable prices. The problem is they aren't very powerful. Remember, you get what you pay for and always try (rent) before you buy.
Hope it helps and good luck!