So there are various corrosion inhibiting oils, however they are NOT all created equal, some definitively work better than others. The better of them tend to contain one of a class of compounds which bond/adhere to the metal surface to form a protective layer. If you'd like a deeper dive on the subject, you may find this video informative:
https://youtu.be/VpRrP3sqQLw
I personally prefer a product called Tuff Glide (in a spray bottle) for protecting my guns, and none have a speck of rust on them. I believe it contains a similar compound to Deoxit, as covered above.
As far as corrosion removal, I have to strongly urge you NOT to scrub it off with steel wool or brass. If the substrate is a straight carbon steel, then by all means have at it with the steel wool, but if it contains any chromium (the stuff that makes stainless steel stainless) you'll be working against it. The reason has to do with how corrosion resistant grades of steel work. You see chromium in steel oxidizes, and forms a protective boundary layer of chromium oxide. If that is violated, by scrubbing on other metals such as carbon steel or brass, the chromium oxide layer can't form and corrosion will continue at that point. This is why stainless steel "pits," where that boundary has failed corrosion will continue to penetrate. Cuprous alloys, such as brass, are also inadvisable because they have a different reduction potential than steel, so cause galvanic corrosion. In plain english, they basically form the second electrode in a battery much like if you stick two different coins in a lemon. In doing so, they promote corrosion, thus are to be avoided.
As far as preventing corrosion goes, aside from wiping down your rifle, dehumidification is your best bet. Water is an important part of the corrosion process, including water in the air. Dehumidifying your gun safe/case/house/shop/whatever is an easy systemic treatment for corrosion. The following is a decent quick-reference for humidity levels and corrosion:
http://dpcalc.org/ As an aside, beyond running a fully snarling compressor-based dehumidifier, there are smaller solutions great for gun cases and safes. Things like these:
https://www.amazon.com/Improved-Eva-dry-333-Renewable-Dehumidifier/dp/B000H0XFCS/ Or if you want to run the dessicant yourself, and you don't need it as a modular pack:
https://www.amazon.com/Dry-Desiccant-Indicating-Industry-Standard/dp/B01I5Y2DG6/ Keep in mind these are just two specific examples out of a massive genre of products.
What do do with existing corrosion? Well there are a couple options. Deoxit and some patience with a q-tip is probably the most gentle strategy. Keep in mind that blueing is also an oxide process, so anything that'll take the rust off can also attack the blueing. You can run a citric acid passivation cycle. You can scrub it off with a synthetic scouring pad. Or you can reach for a chelation agent like Evapo-Rust. Be sure, after cleaning it off though, that you immediately oil it, preferably with something better than WD-40.
I hope that helps. There is really quite a lot of information on this subject, and this is just kind of a quick skim with some simplifications.