I did all of my loans with small local banks in my area and was always happy with the rates and service.

Here are some thoughts on your choices:401k Loan: This can be a good option since you're borrowing from yourself, but it comes with repayment risk, especially if you leave your job.

The typical term of this loan is 12 months and rates range from 10%-12%.

It may or may not show on a credit report, depends on the servicing and you should have the loan serviced.Failure to include the debt on a future loan application is mortgage fraud, wanna go to jail?

Ton's of people with golden shackles of sub 3% rates, epic net shortage, skilled labor shortage, on and on. 

I'm using my VA loan so I don't have to put any money down & can keep money in my account to fund rehab deals. 

Are there specific lenders or servicers that are more likely to call these loans?

It recently dawned on me the idea of a non military affiliated individual assuming a VA loan, would this individual be able to then also gain the benefit of using an IRRRL since they have now acquired a VA loan through assumption?

If the loan is being paid the seller/previous owner has no reason to want off of the loan.

FHA and Conventional loans will allow schooling to count as work history.