OK, a very Eve answer:
It’s a while since I looked at mining in a Venture - or paid any attention to how fast my Skiff mines (I mine for pleasure not income - hi-sec gets me 8m ISK/hr - see final comment).
The figures feel about right from memory: about 5m³/sec keeps going through my mind for a Venture. What that translates to in ISK per hour depends on many things - what you are mining, where you are selling and so forth.
So your figures are about right: the rate is also skill dependant - ORE Frigate and the various mining skills are the important ones; train as high as you can. All those 5%s really add up!
You are right to not think of an expensive fit on a Venture. That makes you a target; generally T2 miners (or meta ones - scoped are good), fill the lows with mining upgrades (T2 if you can), an afterburner, scanner and the biggest (medium) shield extender you can fit in the mid-slots. Go cheap though. I can’t remember if Alpha’s can use T2 miners and upgrades. Drop to meta if needs be.
Add shield extending rigs and you’re good to go. A reasonable tank makes you a less economic kill. It won’t save you, but others will be better targets (it’s a cruel place).
A couple of cheap light drones to pop belt rats is useful.
There is no racial advantage that applies for mining. Racial advantage only really applies early on and is quickly cross trained out.
If you can find a friend to provide mining bursts then great. They can add 20-30% fairly easily - and if they are a good friend they’ll have shield bursts, remote shield boosters and buy ore off you to save running around. But that’s a good friend.
Bursts are cheap, but not free. Be nice, don’t quibble a reasonable offer for ore and feel free to offer to pay for their help if the are being friendly.
Nice people won’t ask to be paid.
Where: hi-sec is fairly safe. Not completely safe, no where is. CONCORD punish offenders. They are not there to save you so keep an eye out and move away from the warp in beacon - go to the far end of the belt.
Low and Null sec. Accept that you will quite likely loose your ship. Find somewhere quiet. Pay attention to local and grid, keep moving (orbit the rock) and be prepared to run. The rocks are more valuable, but you’re running more risk and it can be a pain getting the rocks to a good market. Ninja mining in someone else’s space is a thing and is fun. But it’s fun, not very profitable.
Wormholes. Really exciting, very lucrative, very high chance of dying. You’ll need a probe scanner to find your way around (on a second ship) use lots of bookmarks and make sure your insurance/Will/confessions are done.
A Venture is not a combat ship. It’s an efficient “running away” ship. Use it to mine for pin money or to relax.
Do not for pities sake grind for ISK to buy Plex to pay for Omega. It’s not worth your time and sanity. You will burn out if you treat Eve as a job.