If there are any penalties to using your HELOC in that fashion, you would need to check with your lender. 

My first and third door are here, looking to get a HELOC on one to do some value-ads to the other :)HELOC on investment properties take a decent amount of equity.

I've used HELOCs in this way a number of times.  

HELOCS are awesome.

My preference would be on the maximum loan amount since a HELOC for investment should always be a shorter duration funding.

I prefer the HELOC simply because it gives me more flexibility in my search before I have to begin paying back the note.

If your current home takes longer to sell, make sure you’re comfortable with the HELOC payments in the meantime.

I can get a HELOC on my home for $85K and I can get a HELOC on my commercial building for $50K.I'm NOT a carpenter or a handyman but I'm willing to learn.Having said all that.....I'm really not sure where to start.   

Whether you use a HELOC, or cash out refinance, it just depends on the each property/situation.

3) Why would you use a HELOC to buy?