You can either get paid hourly for your time or allow the time spent to accrue a greater interest stake (although that's trickier).

However, if it goes to eviction, I will not get the money back (and also accrue eviction fees).

If I'm correct, most get HML's and only pay the interest accrued monthly, but I've also read that some are able to defer all principal and interest payments until the loan is paid back.

The indirect overhead cost of running a flip business can still be claimed, but, all direct costs you mention are accrued then reported as Cost of Goods Sold in the year of sale.

I was wondering if the mileage I accrue while driving potential properties can be counted on my taxes?

Investors would accrue and get paid in the end. 

All direct costs for a flip are accrued until the property is sold.  

If you do and they stop the showings I would with hold whatever vacancy costs you accrue as a result of them not allowing showings from their deposit.

Or would you recommend finding a high paying management/finance position elsewhere, accruing capital and teaching myself the industry? 

Usually a payoff is just the remaining principal balance plus interest accrued to the date of payoff, in addition to any other small recording or miscellaneous fees.Are they tacking on deferred interest from 10 years ago?