But B is far from there and really on the edge with the tracks and Erie Ave. 

Our existing mortgage on that house (15 yr at at 4.25%) will be paid in 6 years and yesterday I was quoted a rate of 4.75% for a cash-out 30 yr refi.Tax considerations: we've owned the existing property as a sole proprietor and the Tax Cuts and Job Act has me considering LLC or even possibly C-Corp for tax benefits.

With federal cutting the rates to zero, what to expect on high balance mortgages (loan amount above 500k since its pretty common in bay area). what interest rate to expect to refinance and new home mortgages ?

While I am not surprised rates were cut to zero - bank reserves were also cut to zero as well.

That will likely do more for the market than another rate cut. 

We have considered just staying put in our current house in which we have a tenant that lives with us and basically cuts our mortgage payment in half with their rent payment.

All discretionary purchases are on hold, and I'll be reviewing my recurring/subscription billings to cut charges that are no longer needed. 

Should I just cut the ties as an agent?

The numbers are tight , the cash flow is negative the 1st year (not looking good) , also I didn't see the other 3k for the refi closing so all in all (6k in closing cost) with the market like it is you should be able to make/ find a better deal. a couple of options would be to do the work yourself and cut the cost of the 20k you have to put in it, move into it and pull 80% out that would give you 124k, negotiate the price lower .

And thank you, all hospitals and all of us are really advising everyone to stay home as much as possible for safety!