This is going to be long, but here goes:
Veteran's preference might help you get hired, emphasis on "might". The biggest advantage it would give you is that you'd be able to apply under Non-Competitive Eligibility (NCE) to some (NOT all) jobs. That doesn't mean they have to hire you or even that they
will hire you. It just means that they have the
option of hiring you without going through a formal hiring process (posting a job, holding interviews, screening candidates, etc). They can just say "hey we like this person, let's hire him, he's hired."
That said, if you joined the service (Air Force or otherwise), by the time your service is over, you'll no longer be eligible to apply under Pathways because it will have been too long since you graduated. You'd have to go through other channels. And not all federal jobs have NCE.
(This next paragraph is based somewhat on hearsay, since I don't work for the OPM or anything)
Getting a civil service job (through Pathways or through anything else listed on USAJobs) has a lot to do with the way you word your qualifications. Pay attention to the wording used in the job post. Use the same wording in your application materials. It sounds simplistic, but their software works a lot like the HR software used by public-sector corporations. It filters for keywords and sorts applicants into "Best Qualified" "Qualified" and "Not Qualified" based on what's there. If there are, say, 100 people who pop out as "Best Qualified", those are the ones who'll be referred, then they get reviewed, then some get called and everyone else gets the rejection email. Like someone else said, if the posting lists "managed ABC and used XYZ software to do 123", write "managed ABC and used XYZ software to do 123". Don't write "managed effectively and used advanced software to do complicated mathematics" or whatever. Generalizations are not your friend. Be EXTREMELY specific.
(end hearsay)
Also, make sure you carefully read and follow
everything in the "How to Apply" section, because if you're eligible as GS-05 or GS-07 based on your education, they're going to require you to submit transcripts. If you don't submit everything they ask for, you won't get a call-back.
And keep in mind that federal hiring is notoriously slow, so expect the hiring process to take, at absolute minimum, 6 months. Realistically probably more like 12-18 months. So this isn't the kind of job you want to apply for and wait for a call-back. My suggestion would be carefully work on your application materials and tailor them to each opening, keep in mind that there's a time limit on your eligibility to be hired under Pathways, apply for federal jobs, and continue a job search in the private-sector as well. Keep government employment as a "Plan B" even if it's what you really want to do. Have a "Plan A" career that will allow you to keep developing experience and earning money in the time that it takes for the government to actually process applications and conduct interviews and do background investigations. For example, if you're applying for a job that requires Top Secret level security, even if you've lived the most squeaky-clean life of all time and have no foreign contacts whatsoever, a TS clearance will take an average of 3-5 months to complete, and that's AFTER they've extended a conditional job offer.
Getting hired as a federal employee is a LONG process, especially if you want to be doing high-level mechanical or aerospace engineering work, which is something that would almost definitely require some amount of security clearance. Basically, you need to be doing something in the meantime, preferably working in engineering somehow. That way if you never manage to get that federal job, you're still doing something you're interested in. And if you DO manage to get a fed job somewhere down the line, you'll be building a resume in your field in case your Pathways eligibility times out and you have to apply to professional-level jobs with grade levels based on work experience rather than degree.
But yeah, absolute best case scenario, start to finish, you'd be starting work in about a year from the time you apply to a given job. Do something else in the meantime.
Oh, and use the USAJobs resume builder. Don't apply to federal jobs with your private-sector resume. This is what a federal resume looks like:
https://www.umuc.edu/students/suppor...ral_Resume.pdf
(The one in this example is four pages long. That's not abnormal for a federal resume)