From my experience was pretty seamless (this was probably 2+ years ago)

If you connect and work with an investor-focused real estate agent, preferably one who also invests, then the rest of your team should assemble fairly seamlessly.

Sheets are 70/30 cotton poly blend Big One from Kohl's.

In that case, an appraiser will want to focus on sales of properties with similar houses.Your situation might be a blend of both, down to a micro-market level, which will make it very difficult for an appraiser to really nail it down.

I'm looking for tax implications/benefits ETC.I own an investment firm that allows Canadians to easily and seamlessly invest in US multifamily properties.

I think a blend of the two is a great place to be. 

Option 3 is a blend of the two. 

Depending on how much you plan on taking out relative to your first lien, I would do a blended rate calculation just to make sure that it does not make more sense to refi. 

Solera works seamlessly with my trust company.  

Obviously if your rate is high, it might make sense to completely recapitalize it and kill 2 birds with 1 stone, but if your rate is decent, a HELOC is advantageous because you are not touching the current debt, so your "blended" rate will likely be lower than if you did a cash out refi.