If you already have experience and in-depth market knowledge, I think you should use the vacancy and PM rates that you know are realistic.

We make a combined $50,000 a year, is this a realistic goal?

When is it realistic for me to get in contact with a realtor and start this process?

The realistic answer is no.  

But that's probably hard to find - specially someone who will trust you to pay the 5-7% you promise them.The other (more realistic) option is to call a mortgage broker.

I saw many deals in and around Michigan for 65-85K that would return 800 USD a month or about $1100 a month where I am from.It's easy to see that if I sank 250-350k jn the states I could easily get 5 - 7 deals maybe more If I wholesaled the deals myself I'm seeking honest feedback, Is it a realistic dream to build a portfolio in the USA (Midwest) and combine with 2 yearly inspection trips and maintain a tight communication with people on the ground while living overseas?.

Only you can calculate what that amount will be (after taking into account how much work needs to be done and what you realistically think the ARV will be and what profit you would be happy with).

Any suggestions from the BP community on what is realistic?  

So it might be more realistic to set 7.5% as repairs and 5% as cap ex.  

Also, how much forced appreciation is realistic in terms of a percentage to rehab costs?